LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 


Class 


WORKS  OF  PROF.   A.    S.   MILLER 


PUBLISHED    BY 


JOHN  WILEY  &  SONS. 


A  Manual  of  Assaying. 

The  Fire  Assay  of  Gold,  Silver,  and  Lead,  includ- 
ing Amalgamation  and  Chlorination  Tests.  Third 
Edition,  Revised  and  Enlarged.  12010,  viii-f  148 
pages,  41  figures.  Cloth,  $1.00. 


The  Cyanide  Process. 

An  Introduction  to  the  Cyanide  Process,  includ- 
ing the  Determination  of  the  Applicability  of  the 
Process  to  an  Ore.  Second  Edition,  Revised  and 
Enlarged.  i2mo,  viii-|-95  pages,  28  figuies.  Cloth, 

$1.00. 


THE  CYANIDE  PROCESS 


AN  INTRODUCTION  TO  THE  CYANIDE  PROCESS, 

INCLUDING  THE  DETERMINATION  OF  THE 

APPLICABILITY  OF  THE  PROCESS 

TO  AN  ORE 


BY 

ALFRED   S.   MILLER 
•  i 

FORMERLY  PROFESSOR  OP  MINING,  METALLURGY,  AND  GEOLOGY 

UNIVERSITY  OF  IDAHO 
Author  of  A  Manual  of  Assaying 


SECOND  EDITION,  REVISED  AND  ENLARGED 
FIRST    THOUSAND 


NEW  YORK 

JOHN  WILEY  &  SONS 

LONDON:   CHAPMAN"   &   HALL,    LIMITED 

1906 


f'lERAL 


Copyright,  1903,  1906 

BY 

ALFRED  S.  MILLER 


EGBERT  DRUMMOND,   PRINTER,  NEW  YORK 


PREFACE  TO  THE  SECOND  EDITION. 


As  stated  on  the  title  page,  this  book  is  intended,  as 
"an  introduction  to  the  cyanide  process,  including 
the  determination  of  the  applicability  of  the  process 
to  an  ore."  It  was  written  primarily  for  the  con- 
venience of  the  writer's  students  in  doing  laboratory 
work,  and  the  first  edition  was  printed  for  the  writer. 
The  demand  from  most  of  the  gold-mining  regions  of 
the  world  for  copies  of  this  book  has  made  it  necessary 
to  issue  a  second  edition. 

A  mining  engineer,  after  receiving  a  copy  of  the  first 
edition,  wrote,  "It  is  certainly  the  most  compact  and 
Ho  the  point'  book  on  this  subject  that  is  printed." 
If  the  writer  has  succeeded,  even  in  a  measure,  to 
write  a  "  compact"  and  "to  the  point  "'book  on  this 
subject,  it  should  be  welcomed  by  all  who  are  not 
already  proficient  in  this  subject. 

Figures  9  and  10  are  from  photographs  of  laboratory 
work.  Figures  14,  15,  and  16  are  taken  from  the  cata- 
logue of  the  Hendryx  Electro  Cyanide  Company.  The 
other  illustrations  are  taken,  by  permission,  from  the 
catalogue  of  the  Pacific  Tank  Company. 

Moscow,  IDAHO,  February,  1906. 

iii 

155755 


PEEFACE   TO  THE  FIRST  EDITION. 


A  NUMBER  of  books  on  the  cyanide  process  are  on  the 
market.  Articles  on  this  subject  constantly  appear 
in  the  proceedings  of  scientific  associations,  and  in  the 
mining  and  metallurgical  journals.  It  might,  at  first 
thought,  appear  unnecessary  to  publish  another  book 
on  this  subject,  especially  since  books  cannot  keep 
up  with  the  progress  of  such  a  subject.  But  there 
are  many  mining  men  and  students,  who,  on  account  of 
their  limited  knowledge  of  chemistry,  and  of  the  prac- 
tical operations  of  the  cyanide  process,  are  not  able 
to  receive  much  benefit  from  the  publications  mentioned 
above. 

This  book  has  not  been  written  for  the  expert,  or 
for  the  man  who  " knows  it  all";  but  for  the  larger 
number  of  persons  who  have  no  knowledge  of  this 
subject,  and  are  looking  for  a  book  that  will  give  them 
a  start,  and  sufficient  of  the  fundamental  principles  to 
understand  the  literature  on  this  subject.  It  is  also 
intended  to  serve  the  purposes  of  a  syllabus  and  a 
laboratory  guide. 

Clearness  was  aimed  at  even  at  the  expense  of  repe- 

iv 


PREFACE   TO    THE   FIRST    EDITION.  V 

tition.  Conciseness  is  essential  to  attain  the  object 
sought  in  this  book. 

This  being  largely  a  chemical  subject,  technical 
terms  and  chemical  equations  could  not  be  altogether 
avoided;  nor  would  it  have  been  desirable  to  do  so. 

Acknowledgment  is  due  the  Pacific  Tank  Company 
for  kindly  loaning  the  writer  the  cuts  used  in  illustrating 
this  article. 

Moscow,  IDAHO,  January,  1903. 


CONTENTS. 


PAGE 

INTRODUCTORY 1 

CHAPTER  I. 

GENERAL  DESCRIPTION  OF  THE  CYANIDE  PROCESS 3 

Methods  of  operating  the  Cyanide  Process:  The  Percola- 
tion Method;  The  Agitation  Method;  The  Double- treat- 
ment Method:;  The  Circulating  Method.  Methods  of 
precipitating  the  Gold  from  the  Cyanide  Solutions. 

CHAPTER  II. 

INTERFERING  SUBSTANCES 12 

Acidity;  Base  Metals  (general) ;  Iron;  Soluble  Sulphides; 
Iron  Sulphide;  Copper,  Organic  Matter;  Antimony; 
Arsenic;  Aluminum;  Magnesium;  Cobalt;  Manganese; 
Zinc. 

CHAPTER  III. 

THE  CHEMISTRY  OF  THE  CYANIDE  PROCESS 18 

Chemical  and  Mechanical  Means  of  supplying  Oxygen  to 
the  Solution;  Decomposition  of  Potassium  Cyanide; 
Strength  of  Solutions;  Reactions  in  the  Zinc  Boxes; 
Determining  the  Strength  of  Solutions;  Methods  to 
save  Calculations ;  To  bring  a  Weak  Potassium  Cyanide 
Solution  up  to  Any  Strength ;  To  reduce  the  Strength 

vii 


Vlll  CONTENTS. 

PAGE 

of  a  Solution;  To  make  a  Definite  Volume  of  a  Weaker 
Solution  from  a  Stronger  Solution;  Methods  for  assay- 
ing Cyanide  Solutions;  Testing  Cyanide  Solutions  con- 
taining Zinc ;  Titrating  Complex  Solutions. 

CHAPTER  IV. 

DETERMINING  THE  APPLICABILITY  OF  THE  CYANIDE  PROCESS 

TO  AN  ORE 35 

Extraction  Tests;  Acidity;  Consumption  of  Cyanide; 
Precipitation  Tests ;  Amalgamation  Tests. 

CHAPTER  V. 

NOTES 43 

Strength  of  Solutions;  Calcining;  Roasting;  Crushing; 
The  Clean-up ;  Used  Solutions  Less  Powerful  than  Fresh 
Solutions  of  the  Same  Strength;  Silver  Ores;  Other 
Notes;  Useful  Information. 

CHAPTER  VI. 

SHORT  DESCRIPTIONS  OF  SOME  CYANIDE  PROCESSES 52 

McArthur-Forest  Process;  Siemens-Halske  Process;  The 
Pneumatic  Process;  The  Betty  Process;  The  Godbe 
Agitation  Process;  The  Begeer  Cyanide  Process;  The 
Decantation  Process;  Precipitation  by  Zinc  Dust;  The 
Bromo-Cyanogen  Process;  The  Holderman  Process; 
The  Moore  Process;  The  Hendryx  Process;  Sample 
Specifications  and  Prices  of  Cyanide  Plants ;  Illustra- 
tions of  Vats,  False  Bottoms,  and  Cyanide  Plants. 

APPENDIX. 

VOLUMETRIC  ANALYSIS 80 

ATOMIC  WEIGHTS ....,.,.   90 


UNIVERSITY 


THE  CYANIDE  PROCESS, 


INTRODUCTORY. 

THE  first  use  of  potassium  cyanide  to  dissolve  gold 
in  ores,  on  a  commercial  scale,  is  of  comparatively  recent 
date.  McArthur  and  Forest  took  out  a  patent  on  the 
cyanide  process  in  England  in  1887,  and  in  the  United 
States  in  1889.  It  was  some  years  after  this  before  a 
success  was  made  of  the  process,  and  not  until  a  success 
had  been  made  of  the  process  elsewhere  did  it  come 
into  use  in  America. 

That  gold  is  soluble  in  potassium  cyanide  was  known 
for  a  long  time.  Hagan  mentioned  it  in  1806.  Dr. 
Wright  used  gold-cyanide  solution  in  electroplating 
in  1840.  Eisner  published  his  observations  in  1844, 
claiming  that  the  solution  of  the  metals  is  due  to  the 
action  of  the  oxygen  aborbed  from  the  air,  which  "  decom- 
poses part  of  the  cyanide.'^) 

J.  H.  Rae  took  out  the  first  patent  in  the  United 
States  in  1867,  for  the  extraction  of  gold  by  a  "  current 
of  electricity  and  suitable  solvents  or  chemicals,  such, 
for  instance,  as  cyanide  of  potassium."  This  was 


2  THE    CYANIDE   PROCESS. 

followed  by  other  patents  from  time  to  time;  but  none 
of  these  processes  came  into  general  use,  until  McArthur 
and  Forest  took  out  their  patents.  ^^^^/ 

The  process  was  developed  by  many  experimenters, 
and  practical  workers  of  the  process.  In  many  instances 
the  same  facts  have  been  discovered  independently  by 
workers  in  different  parts  of  the  world.  This  makes  it 
impossible  to  credit  everything  that  is  known  of  this 
subject  to  the  person  that  may  think  he  deserves  such 
credit.  As  this  is  largely  a  chemical  subject,  much 
that  is  known  depends  on  the  general  principles  of 
chemistry,  which  are  the  common  property  of  all. 


CHAPTER  I. 
GENERAL  DESCRIPTION  OF  THE  CYANIDE  PROCESS. 

/  A  DILUTE  solution  of  potassium  cyanide  dissolves 
gold  and  silver  contained  in  crushed  ore,  and,  with 
some  exceptions,  does  not  attack,  to  a  large  degree 
(during  the  time  necessary  to  dissolve  a  large  per- 
centage of  the  gold),  any  of  the  other  constituents  .of 
the  ore.  The  gold  and  silver  are  then  precipitated 
from  the  solution,  and,  after  proper  treatment,  cast 
into  bars.  This  constitutes  what  is  known  as  the 
"Cyanide  Process."  ; 

Different  methods  have  been  devised  by  which  these 
results  are  attained.  A  general  idea  of  the  working 
of  this  process  may  be  obtained  from  Fig.  1,  which 
is  a  laboratory  plant  by  which  about  100  Ibs.  of  ore  can 
be  treated  at  a  time.  A  potassium  cyanide  solution 
of  the  best  strength  *  is  put  into  the  uppermost  tank. 
The  ore,  crushed  to  the  best  size,*  is  put  into  the  next 
lower  tank.  Above  the  bottom,  this  tank  has  a  per- 
forated false  bottom  which  is  covered  with  duck  filter- 
cloth.  The  solution,  from  the  uppermost  tank,  enters 
the  tank  containing  the  ore  from  the  bottom.  After 
the  ore  has  soaked  the  best  length  of  time,*  the  gold- 

*  As  determined  by  experiment. 


THE   CYANIDE   PROCESS. 


FIG.  1. — Laboratory  Cyanide  Plant. 


GENERAL   DESCRIPTION.  5 

bearing  solution  *  is  drawn  off  from  below,  and  passed 
through  the  rectangular  wooden  box  below.  This  box 
is  divided  into  six  large  and  six  small  compartments. 
The  solution  flows  down  through  the  small  compart- 
ments and  up  through  the  large  compartments  (for 
arrangement  of  box,  see  Fig.  2).  Each  large  compart- 
ment is  fitted  with  a  wire  screen,  near  the  bottom, 
above  which  the  compartment  is  filled  with  zinc  shav- 


PIG.  2. — Wooden  Zinc-boxes. 

ings.  The  zinc  precipitates  the  gold  and  silver  from 
the  solution,  and  the  solution  runs  down  into  the 
lowest,  or  sump  tank.  From  this  tank  the  solution  is 
poured  back  (pumped  back  in  large  works,  see  Fig.  5) 
into  the  uppermost  tank,  enough  strong  solution  is 
added  to  bring  the  used  solution  to  the  strength  it  had 
before  it  was  put  on  the  ore,  the  ore  in  the  next  lower 
tank  is  replaced  by  fresh  ore,  and  all  the  other  operations 
are  repeated  as  before. 

*  Generally,  the  first  solution  of  potassium  cyanide  is  followed 
by  a  weaker  solution,  or  a  weak  solution  is  used  first,  followed  by 
a  stronger  solution;  and  the  last  potassium  cyanide  solution  is 
followed  by  a  water-wash. 


THE    CYANIDE   PROCESS. 


FIG.  3. — Iron   Zinc-boxes. 

These  are  light  rectangular,  sheet-steel  boxes,  absolutely  water- 
tight and  thoroughly  coated  with  acid-proof  paint. 

In  service  the  boxes  are  arranged  in  series  as  shown.  Each 
box  has  two  compartments  and  the  solution  passes  down  the  narrow 
and  up  through  the  large  compartment  in  which  the  zinc  shavings 
are  placed,  and  overflows  into  the  next  box. 


FIG.  4. — Improved  Iron  Zinc-boxes. 

It  will  be  noticed  that  the  box  is  made  round  instead  of  square; 
this  avoids  the  necessity  of  filling  out  corners.  Each  compart- 
ment has  a  capacity  of  one  cubic  foot  of  shavings.  The  iron  is 
thoroughly  protected  by  acid-proof  paint  and  every  box  is  fitted 
with  a  perforated  iron  shavings-tray.  Each  box  forms  one  com- 
partment, and  generally  six  or  more  compartments  are  used  in 
series. 


GENERAL   DESCRIPTION. 


8 


THE    CYANIDE    PROCESS. 


Methods  of  operating  the  Cyanide  Process.  —  The 
principal  methods  of  operating  the  cyanide  process 
are  the  percolation  method  and  the  agitation  method, 
or  some  modification  of  these  methods. 

The  Percolation  Method. — In  the  percolation  method 
the  solution  is  allowed  to  percolate  through  the  ore. 


FIG.  6. — Agitator,  Style  A.  When  the  extraction  is  complete 
the  agitators  are  discharged  into  leaching  vats,  and  filtration  is 
accomplished  by  means  of  vacuum  pumps,  or  the  pulp  is  filter 
pressed. 

This    method    has    been    described     under  •"  General 
Description  of  the  Cyanide  Process." 

The  Agitation  Method.— In  the  agitation  method, 
after  the  cyanide  solution  is  put  on  the  ore,  the  ore 
is  agitated  by  mechanical  agitators  (shown  in  Figs.  6 


GENERAL   DESCRIPTION.  9 

and  7\  or  by  cold  or  hot  compressed  air,  which  is 
allowed  to  enter  at  the  bottom  of  the  tank  (Pneumatic 
Process,  Figs.  12  and  13).  The  air  agitates  the  ore, 
and  supplies  oxygen.  The  use  of  oxygen  in  a  cyanide 
solution  is  explained  under  "The  Chemistry  of  the 
Process." 


FIG.  7.— Agitator,  Style  B. 

By  the  agitation  method  more  gold  is  dissolved  than 
by  the  percolation  method;  but  power  and  additional 
potassium  cyanide  are  consumed/^  Agitation  may 
shorten  the  necessary  time  of  contact  of  the  solution 
with  the  ore  sufficiently  that  there  will  be  less  consump- 
tion of  cyanide  by  agitation  than  by  percolation. 


10  THE    CYANIDE    PROCESS. 

s  The  Double-treatment  Method  consists  in  treating 
the  ore  with  a  cyanide  solution  in  a  tank;  and,  after 
draining,  the  ore  is  transferred  to  another  tank,  and 
again  treated  with  a  stronger  or  weaker  solution,  which 
is  sometimes  followed  by  one  or  two  weaker  solutions. 


FIG.  8. — Agitation,  by  Centrifugal  Pump. 

This  arrangement  is  used  at  many  cyanide  plants,  particularly 
for  the  agitation  of  slimes  in  connection  with  decantation  or  filter- 
pressing.  One  advantage  is  that  agitation  can  be  readily  started 
even  if  the  material  has  settled  compactly  on  the  bottom  of  the 
tank,  because,  the  suction-pipe  being  connected  by  a  loose  elbow, 
suction  can  be  started  on  top  of  the  charge,  and  as  the  material 
loosens  up  the  weight  of  the  pipe  will  cause  it  to  gradually  settle 
until  finally  the  suction  takes  place  at  the  bottom  of  the  tank. 

In  the  Circulating  Method  the  solution  is  allowed  to 
percolate  through  the  ore,  and  is  constantly  pumped 
back  on  the  ore — the  ore  being  kept  covered  with  the 
solution  during  the  time  of  the  treatment. 


GENERAL   DESCRIPTION.  11 

^Sometimes,  after  the  solution  is  put  on  the  ore,  the 
ore  with  the  solution  is  pumped  from  one  tank  to  another, 
which  agitates  the  ore  and  supplies  oxygen. 

Methods  of  precipitating  the  Gold  from  Cyanide 
Solutions. — Precipitation  of  the  gold  from  cyanide  solu- 
tions is  effected  by  zinc  shavings  (McArthur-Forest 
Process);  by  electricity  (Siemens-Halske  Process) \ 
by  zinc  shavings  covered  with  lead  (The  Betty  Process) ; 
by  electricity  on  amalgamated  copper  plates  covered 
with  a  layer  of  mercury  (The  Pelatan-Clerici  Process); 
by  zinc  filaments;  by  sifting  zinc  dust  into  the  gold- 
bearing  cyanide  solution,  and  keeping  the  solution 
with  the  zinc  dust  in  agitation  by  compressed  air; 
by  charcoal.  (  (VA^^a^^ 


CHAPTER  II. 
INTERFERING   SUBSTANCES. 

Acidity .-^If  the  ore  contains  an  acid,  decomposition 
of  potassium  cyanide  results)  ^Sulphide  ores  or  tailings, 
which  have  undergone  oxidation,  usually  contain  sul- 
phuric aQid.)rThe  soluble  acid  can  be  washed  out  of 
the  ore  by  water,  or  the  soluble  and  the  insoluble  acids 
can  be  neutralized  by  lime  or  soda?)  A  large  excess 
of  lime  or  soda  must  be  avoided,  as  it  ^consumes  zinc, 
if  zinc  is  used  to  precipitate  the  gold;  /and,  with  ore 
containing  a  soluble  sulphide,  an  alkaline  sulphide 
would  form,  which  interferes  with  the  extraction. 

When  sulphides*  of  alkaline  earths  only  are  present, 
the  lime  may  be  added  to  the  ore  or  to  the  solution; 
but  when  ferrous  salts  are  present,  an  alkaline  wash, 
followed  by  a  water-wash,  should  precede  the  appli- 
cation of  the  cyanide  solution  (see  under  Iron). 

Base  Metals. — It  has  been  generally  stated  that 
weak  solutions  of  potassium  cyanide  attack  the  com- 
pounds of  the  base  metals  less  in  proportion  to  the 
gold  than  strong  solutions.  (This  has  been  attributed 
by  McArthur  and  Forest  to  the  "selective  action"  of 
potassium  cyanide  for  gold.  W.  A.  Dixon  considers 
this  action  to  be  due  to  the  larger  proportion  of  oxygen 

12 


INTERFERING  SUBSTANCES.  13 

to  cyanide  in  a  weak  solution,  on  the  theory  that  cyanide 
attacks  free  gold  so  long  as  free  oxygen  is  present, 
(then  attacks  the  compounds  of  the  base  metals^)  Julian^ 
and  Smart  *  state  that  the  proportion  of  gold  and  min- 
eral matter  of  the  ore  dissolved  in  a  weak  solution  is 
the  same  as  in  a  strong  solution:  "the  same  propor- 
tionality exists  with  solutions  of  all  strengths  within 
working  limits."  For  practical  purposes  it  is  sufficient 
to  know  that  a  weak  solution  of  potassium  cyanide 
gives  better  results  than  a  strong  solution. 

Base  metals  dissolve  regardless  of  the  strength  of  the 
solution,  or  the  amount  of  oxygen  it  contains r  (Base 
metals  are  usually  in  the  ore  in  the  form  of  compounds, 
and  gold  in  the  metallic  state .")  The  compounds  of  the 
base  metals  exchange  their  bases  for  the  potassium  in 
the  potassium  cyanide,  and  form  a  compound  with  the 
cyanogen  (metalepsy),  or  cause  some  other  compound  to 
be  formed  with  the  cyanogen  j  Metallic  gold  being  unable 
to  replace  the  potassium  in  the  potassium  cyanide,  it 
becomes  necessary  to  add  some  element  or  substance, 
as  oxygen,  bromine,  etc.,  which  will  set  the  cyanogen 
free,  which  will  then  dissolve  the  gold,  and  form  a  com- 
pound with  it,  or  a  gold-potassium  cyanide" ) 

When  a  solution  contains  the  required  proportion  of 
oxygen  to  dissolve  the  gold,  the  gold  is  more  rapidly 
dissolved  than  when  a  solution  contains  less  oxygen, 
which  leaves  the  solution  weaker  in  cyanide  to  be  acted 
on  by  the  base  metals.; 

The  action  of  potassium  cyanide  solution  on  com- 

*  "  Cyaniding  Gold  and  Silver  Ores"  by  H.  Forbes  Julian  and 
Edgar  Smart. 


14  THE    CYANIDE    PROCESS. 

pounds  of  the  base  metals  depends  somewhat  on  the 
physical  condition  and  the  chemical  combination  of 
these  metals.  Compounds  of  zinc  and  copper  physically 
hard  are  generally  not  much  attacked  by  cyanide  solu- 
tion, freshly  precipitated  oxides  or  hydrates  of  iron, 
zinc,  copper,  and  lead,  which  may  result  from  an  alka- 
line treatment  of  the  ore,  are  more  readily  dissolved 
than  gold  by  a  potassium  cyanide  solution. N  The  car- 
bonates of  the  metals  are  also  attacked  by  the  cyanide 
solution. 

Iron.4rlron  in  the  ferrous  condition  is  attacked  by 
potassium  cyanide  solution,  and  thus  consumes  cyanide. 
Ferrous  oxide  or  ferrous  hydrate  in  the  ore,  or  resulting 
from  a  lime  or  soda  wash  on  ore  containing  ferrous  com- 
pounds, should  be  oxidized  to  the  ferric  condition,  by 
free  access  of  air,  before  the  cyanide  solution  is  applied, 

(Basic  ferrous  salts  resulting  from  oxidation  of  ore  or 
tailings  cannot  be  washed  out  by  water,  but  they  act 
on  the  potassium  cyanide.  By  neutralizing  these  by 
lime  or  soda  (see  under  Acidity),  ferrous  oxide  and 
ferrous  hydrate  are  formed,  which  should  be  oxidized 
to  the  ferric  condition,  by  free  access  of  air,  before  the 
cyanide  solution  is  applied/) 

Metallic  Iron  in  a  state  of  fine  division  consumes  much 
cyanide.  If  the  ore  contains  fine  iron  (some  of  which 
may  be  the  result  of  crushing  the  ore  in  iron  crushers 
and  other  iron  machinery)  or  magnetic  iron,  separate 
such  iron  from  the  ore  by  magnetic  separators,  and,  if 
it  has  sufficient  values  to  pay  to  treat  it,  roast  it  to 
ferric  oxide.  It  may  need  regrinding.  It  can  then 
be  treated  separately  or  with  the  ore, 


INTERFERING    SUBSTANCES.  15 

Soluble  Sulphides. — Soluble  sulphides  decompose  po- 
tassium cyanide,  and  form  alkaline  sulphides,  which 
interfere  with  the  extraction.y^The  percentage  of  ex- 
traction falls  with  the  accumulation  of  the  alkaline 
sulphides  in  the  solution.  The  sulphur  in  the  alkaline 
sulphides  can  be  removed  from  the  solution  by  pre- 
cipitation with  lead  salts,  or  changed  to  different  com- 
pounds by  oxidizers. 

Soluble  sulphides  should  be  turned  into  inert  com- 
pounds before  the  cyanide  solution  is  applied"}  Dead 
roasting  before  cyaniding  is  probably  the  only^  success- 
ful method  so  far  applied.  Roasting  to  sulphates  and 
washing  the  sulphates  out  by  a  preliminary  water-wash 
has  not  proved  successful,  on  account  of  the  difficulty 
of  turning  all  the  sulphide  into  sulphates  in  this  way. 

McArthur  and  Ellis  have  covered  by  patent  the  use 
of  suitable  salts  or  compounds  which,  when  added  to 
the  ore  or  solution,  will  form  with  the  sulphur  of  the 
sulphide  an  inert  sulphide.  For  this  purpose,  they 
give  preference  to  the  metallic  compounds  in  the  fol- 
lowing order:  Salts  or  compounds  of  lead,  such  as 
plumbates,  carbonates,  acetates,  or  sulphates  of  lead; 
sulphate  or  chloride  of  manganese,  zincates,  oxides,  or 
>  chloride  of  mercury,  ferric  hydrate  or  oxide.  The 
amount  to  be  used  must  be  ascertained  for  each  ore  by 
trials  of  a  few  samples. 

Copper. — Copper  is  attacked  by  cyanide  solution,  and 
thus  consumes  cyanide  (see  Copper,  under  Base  Metals). 
If  the  gold  is  precipitated  by  zinc  shavings,  the  copper 
precipitates  on  the  zinc,  forming  a  coating  which 
prevents  the  precipitation  of  gold.  An  addition  of 


16  THE    CYANIDE    PROCESS. 

potassium  cyanide  solution  to  the  gold-bearing  solu- 
tion, before  it  enters  the  zinc-boxes,  or  a  coating  of 
lead  on  the  zinc  by  dipping  the  zinc  shavings  into  a  1% 
or  2%  solution  of  lead  acetate,  before  they  are  put 
into  the  zinc-boxes,  are  proposed  remedies. 

Cyanide  solutions  containing  0.3%  or  over  of  copper 
yield  very  poor  results  in  extraction.*  To  remove 
most  of  the  copper  from  the  cyanide  solution,  by  the 
lead-zinc  couple,  Superintendent  Higgins  of  the  Creston- 
Colorado  plant,  Minas  Prietas,  Sonora,  Mexico,  gives 
the  following  description,  as  practiced  at  that  plant: 
"The  solution  coming  from  the  tanks  titrates  about 
0.23%  KCN  (potassium  cyanide),  and  flows  first 
through' fourteen  ordinary  zinc  launders,  18x2.5  X 2. 5  ft. 
in  size,  where  the  fine  product  is  collected;  secondly, 
from  these  launders  the  solution  is  taken  through  six 
other  launders  with  zinc-lead  in  each  compartment.  I 
use  1.5  Ibs.  lead  acetate  to  15  Ibs.  zinc  shavings;  in 
other  words,  about  160  Ibs.  of  lead  acetate  for  7500  tons 
ore."  The  lead-zinc  couple  is  made  by  dissolving  in 
distilled  water,  in  each  compartment  of  the  zinc -boxes 
used  for  this  purpose,  1.5  Ibs.  of  lead  acetate,  after  which 
15  Ibs.  of  zinc  shavings  are  pressed  into  each  com- 
partment, and  allowed  to  stand  for  half  an  hour  or 
longer.  The  solution,  after  passing  through  the  four- 
teen ordinary  zinc-boxes,  passes  through  the  lead- 
zinc  boxes,  where  a  large  per  cent,  of  the  copper  is 
removed. 


*  W.  H.  Virgoe,  Institute  of  Mining  and  Metallurgy,  December 
1901. 


SUBSTANCES.  17 

The  removal  of  the  copper  from  the  ore  by  a  prelimi- 
nary treatment  by  sulphuric  acid,  followed  by  a  water- 
wash,  before  the  cyanide  solution  is  applied,  may  prove 
satisfactory,  where  the  value  of  the  ore  permits  such 
treatment  at  a  profit} 

Organic  Matter. — Organic  matter  precipitates  gold, 
and  extracts  oxygen  from  the  solution.  Leaves,  chips 
of  wood,  roots,  and  all  other  organic  matter  should  be 
kept  out  of  the  water  used,  and  out  of  the  ore  or  tailings 
treated. 

Antimony,  arsenic,  iron,  aluminum,  magnesium, 
cobalt,  manganese,  zinc,  interfere  to  a  smaller  or  larger 
degree,  according  to  the  physical  condition  and  chem- 
ical combination  in  which  they  are  found. 


CHAPTER  III. 
THE  CHEMISTRY  OF  THE  CYANIDE  PROCESS. 

IT  is  generally  accepted  that  oxygen  is  necessary  to 
dissolve  metallic  gold  by  a  solution  of  potassium  cyan- 
ide, unless  other  substances  are  added  that  combine 
with  the  potassium  and  set  the  cyanogen  *  free.  Eisner's 
equation  is  as  follows : 

2Au  +  4KCN  +   0  +  H20  =  2AuK(CN)2  +  2KOH 

(Gold)       (Potassium    (Oxygen)    (Water)         (Gold-potassium         (Potassium 
cyanide)  cyanide)  hydrate) 

The  equation  for  the  solution  of  metallic  silver  is 
similar.  There  are  other  equations  offered  by  different 
persons  for  the  solution  of  gold,  but  all  such  equations 
contain  oxygen.  l^For  the  purpose  of  dissolving  a  higher 
percentage  of  gold  in  less  time,  oxygen  is  sometimes 
supplied  by  the  use  of  chemicals,  or  by  mechanical 
devices/) 

Among  the  chemicals  that  have  been  used  are  potas- 
sium permanganate,  barium  oxide,  sodium  peroxide, 
manganese  dioxide,  hydrogen  peroxide,  bleaching-pow- 


By  cy-an'o-gen  is  meant  the  radical  (CN). 

18 


THE    CHEMISTRY    OF  THE   CYANIDE   PROCESS.         19 

der,  etc.  The  oxygen  may  destroy  some  of  the  potas- 
sium cyanide: 

KCN  +  0=KCNO, 
2KCNO + 3H20 = K2C03  +  C02 + 2NH3. 

->When  chemicals  are  used  that  combine  with  the 
potassium  and  set  the  cyanogen  free,  no  oxygen  is 
needed  to  dissolve  the  gold.  This  may  be  illustrated 
by  the  use  of  cyanogen  bromide: 

CNBr  +  3KCN + 2Au = 2K  Au(CN)  2 + KBr . 

~  Among  the  mechanical  devices  employed  to  supply 
oxygen  are  the  forcing  of  compressed  air  through  the 
solution  and  pulp  (Pneumatic  process),  running  the 
cyanide  solution,  before  using,  through  a  centrifugal 
pump  which  has  air  connection  (Begeer  process),  and 
allowing  the  solution  to  run  through  open  launders. 

Decomposition  of  Potassium  Cyanide.  —  This  sub- 
ject has  been  discussed  to  some  extent  under  the  sub- 
ject of  Interfering  Substances.  The  mineral  acids  and 
many  organic  acids  decompose  potassium  cyanide. 
Carbonic  acid  decomposes  potassium  cyanide: 

2KCN  +  C02  +  H20  -  2HCN +K2C03. 

Ore  containing  oxidized  iron  pyrites  usually  contains 
some  sulphuric  acid.  With  such  ore  the  potassium 
cyanide  solution,  by  several  reactions  and  contact 
with  the  air,  forms  Prussian  blue.  This  shows  a  large 
waste  of  cyanide.  A  mixture  of  ferrous  and  ferric  sul- 


20  THE   CYANIDE    PROCESS. 

phates  with  potassium  cyanide  also  forms  Prussian 
blue.  This  can  be  prevented  by  keeping  the  solution 
alkaline,  ^his  is  known  as  protective  alkalinity.  Solu- 
tions work  well  on  some  ores  with  a  protective  alkalinity 
up  to  0.3%  or  more.  It  should  be  borne  in  mind  that 
when  soluble  sulphides  are  in  the  ore,  the  alkali  will 
form  alkaline  sulphides  with  the  sulphur,  which  inter- 
fere with  the  extraction, 

The  action  of  the  potassium  cyanide  on  the  com- 
pounds of  zinc,  aluminum,  and  other  compounds  has 
already  been  referred  to  under  Interfering  Substances. 

Strength  of  Solutions.  —  Several  experimenters  have 
found  that  the  rate  of  the-  solution  of  gold  in  potassium 
cyanide  solutions  increases  from  very  weak  solutions 
to  solutions  containing  0.25%  potassium  cyanide;  after 
which  the  rate  decreasesT^It  has  been  found  (by 
Maclaurin)  that  0.01%  potassium  cyanide  solution  dis- 
solves oxygen  at  about  the  same  rate  as  ordinary 
water,  and  that  this  power  increases  up  to  0.25%  or 
0.3%,  after  which  it  diminishes. 

Weak  solutions  dissolve  more  gold  per  unit  of  potas- 
sium cyanide  than  strong  solutions  in  the  same  time. 
The  weakest  solution  that  gives  the  best  economical 
results,  as  shown  lw  actual  experiment  with  the  ore, 
should  be  employed) 

Reactions  in  the  Zinc-boxes. — The  precipitation  of 
gold  and  silver  by  zinc  was  considered  merely  the  sub- 
stitution of  the  zinc  for  the  gold  and  silver,  but  as  free 
potassium  cyanide'  must  be  present  in  the  solution  to 
effect  the  precipitation,  other  equations  have  been 
offered  to  explain  the  precipitation.  As  this  subject 


THE   CHEMISTRY    OF   THE    CYANIDE    PROCESS.         21 

has  not  been  settled,  the  equations  have  been  omitted 
here. 

Determining  the  Strength  of  Solutions. 

To  determine  the  Strength  of  the  Potassium  Cyanide 
Solutions. — The  determination  of  the  potassium  cyanide 
in  a  solution,  by  silver  nitrate,  is  based  on  the  fact  that 
the  silver  cyanide,  formed  by  the  reaction  of  silver 
nitrate  on  potassium  cyanide,  is  dissolved  as  long  as 
free  potassium  cyanide  is  present,  forming  the  double 
cyanide  of  potassium  and  silver: 

AgN03  +  KCN  =  AgCN  +  KN03, 

170  65 


~KAg(CN)2. 

65 

Expressing  the  reactions  by  one  equation, 
AgN03     +     2KCN     =     KAg(CN)2     +     KN03 

(Silver  nitrate)  (Potassium  (Potassium  (Potassium 

cyanide)  silver  cyanide)  nitrate) 

170  130 

When  all  the  potassium  cyanide  is  converted  into  a 
soluble  double  salt  of  potassium  and  silver  cyanide, 
KAg(CN)2,  any  addition  of  silver  nitrate  will  produce 
a  permanent  white  precipitate  of  the  simple  silver 
cyanide : 

K  Ag(CN)  2  +  AgN03  =  2AgCN + KN03. 

If  17  grams  silver  nitrate  are  dissolved  in  distilled 
water  and  diluted  to  1000  cubic  centimeters  (N/10 

^   OF  THE    " 
UNIVERSITY 

OF 


22  THE   CYANIDE   PROCESS. 

normal  solution),  in  1  cubic  centimeter  there  is  0.017 
gram  silver  nitrate;  and  each  cubic  centimeter  silver 
nitrate  corresponds  to  0.013  gram  potassium  cyanide: 

170 : 130::  0.017  :x.    x  =  0.013 

By  multiplying  the  number  of  cubic  centimeters  of 
silver  nitrate  consumed,  before  a  permanent  precipitate 
occurs,  by  0.013,  the  weight  of  the  potassium  cyanide 
is  found  in  the  solution  tested;  from  which  the  per- 
centage strength  *  can  be  calculated. 
)^ome  potassium  cyanide  on  the  market  contains 
sodium  cyanide.  A  sample  containing  sodium  cyanide 
reported  as  potassium  cyanide  would  show  the  solution 
to  be  stronger  in  cyanogen  than  it  is.  Sodium  cyanide 
contains  53  per  cent,  cyanogen,  and  potassium  cyanide 
only  40  per  cent. : 

AgN03 + 2NaCN  =  NaAg(CN)2  +  NaN03. 

170  98 

170 : 98::  0.017  :X.    X  =  0.0098 

One  cubic  centimeter  of  a  deci-normal  silver  nitrate 
solution  corresponds  to  0.0098  gram  sodium  cyanide. 
By  determining  the  percentage  of  sodium  in  the  potas- 
sium cyanide,  the  per  cent,  of  cyanogen  can  be  calculated. 

*  By  percentage  strength  is  meant  the  amount  in  grams  in 
100  cubic  centimeters.  For  example,  by  dissolving  1  gram  pure 
potassium  cyanide  in  water,  and  diluting  the  solution  until  the 
whole  solution,  containing  the  1  gram  potassium  cyanide,  measures 
100  cubic  centimeters,  we  have  a  1  per  cent,  solution  of  ootassium 
cyanide. 


THE   CHEMISTRY    OF   THE    CYANIDE    PROCESS.         23 

Methods  to  save  Calculation. — If  13  cubic  centimeters 
of  the  potassium  cyanide  solution  to  be  tested  are 
titrated  with  the  deci-normal  silver  nitrate  solution,  the 
number  of  cubic  centimeters  of  the  silver  nitrate  solu- 
tion consumed,  divided  by  10,  gives  the  percentage  of 
the  potassium  cyanide  in  the  solution. 

The  silver  nitrate  solution  can  be  made  of  any  strength 
to  save  calculation.  If  13.08  grams  pure  silver  nitrate 
are  dissolved  in  distilled  water  and  diluted  to  1000 
cubic  centimeters,  and  10  cubic  centimeters  of  the 
potassium  cyanide  solution  are  titrated  by  this  silver 
nitrate  solution,  each  cubic  centimeter  silver  nitrate 
consumed  corresponds  to  0.1  per  cent,  potassium  cya- 
nide; or  by  dividing  the  number  of  cubic  centimeters 
of  silver  nitrate  consumed  by  10,  the  percentage 
strength  of  the  potassium  cyanide  is  obtained,  as  above. 
(  The  action  on  the  potassium  cyanide  solution  of  the 
oxygen  in  the  air,  or  the  oxygen  supplied  by  oxidizers, 
may  result  in  the  formation  of  ammonia. }  As  ammonia 
dissolves  silver  cyanide,  and  thus  the  titration  would 
indicate  too  high  results,  it  is  best  to  add  two  or  three 
drops  of  a  2%  solution  of  potassium  iodide  to  the 
sample  of  potassium  cyanide  solution  before  titrating 
it  with  the  silver  nitrate.  The  pale-yellow  precipitate 
which  forms,  after  all  the  potassium  cyanide  is  con- 
sumed, is  almost  insoluble  in  ammonia.  If  much  free 
alkali  is  present,  the  results  may  be  too  high. 

To  a  potassium  cyanide  solution  containing  copper, 
two  or  three  drops  of  a  2%  solution  of  potassium  iodide 
should  be  added  before  titrating  it  with  the  silver 
nitrate  solution.  Too  much  of  the  potassium  iodide 


24  THE    CYANIDE    PROCESS. 

affects  the  results  when  copper  or  much  free  alkali  is 
present. 

In  some  cyanide  plants  the  sample  of  potassium 
cyanide  is  filtered  through  a  little  quicklime  before  it 
is  titrated  with  the  silver  nitrate  solution. 

The  strength  of  the  potassium  cyanide  solution  may 
be  obtained  by  titrating  it  with  a  standard  solution  of 
iodine  in  potassium  iodide,  using  starch  solution  as  an 
indicator : 

2I+KCN  =  KI  +  ICN 

The  iodine  solution  may  be  standardized  by  a  sodium 
thiosulphate  solution  of  known  strength. 

To  bring  a  Weak  Potassium  Cyanide  Solution  up  to 
Any  Strength. — A  strong  solution  of  potassium  cyanide  is 
made  by  dissolving  potassium  cyanide  in  a  separate  tank, 
which  solution  is  used  to  bring  the  working  solution  up  to 
the  required  strength,  after  the  latter  has  been  in  contact 
with  the  ore,  and  the  gold  has  been  separated  from  it. 

For  example,  suppose  50,000  gallons  of  working 
solution  of  0.25  per  cent,  strength,  after  having  been 
in  contact  with  the  ore  and  the  gold  having  been  sepa- 
rated from  it,  has  been  reduced  to  0.10  per  cent,  strength. 
How  much  of  a  10  per  cent,  solution  will  it  take  to 
bring  the  0.10  per  cent,  solution  of  50,000  gallons  up  to 
0.25  per  cent,  strength? 

Let  a  =  the  strong  solution,  10%  strength; 

b  =  the  working  solution  after  using,  0.10%  strength ; 
c  =  the    working    solution    before    using,    0.25% 
strength; 


THE   CHEMISTRY   OF  THE   CYANIDE   PROCESS.        25 

d  =  the  number  of  tons,  Ibs.,  gallons,  etc.  (in  this 
example  50,000  gallons),  working  solution  of 
0.10%  strength  to  be  raised  to  0.25%  strength. 

c-b 

—^Xd  =  gallons  10  per  cent,  solution  to  be  added  to 

the  0.10  per  cent,  solution  to  bring  it  up 
to  0.25  per  cent,  strength. 

'-  X 50,000  =  769. 23  gallons  10  per  cent,  solution 
1U  —  O.Zd  .          iii 

to  be  added. 


-  To  reduce  the  Strength  of  a  Solution. — Suppose  we 
have  40,000  gallons  of  a  solution  of  0.24%  strength, 
and  we  want  to  reduce  it  to  0.10%  strength: 

0.10:0.24:  :40,000:Z.    Z  =  96,000  gallons. 

Add  water  to  the  40,000  gallons  until  the  whole 
volume  reaches  96,000  gallons,  or  add  56,000  gallons 
water  (96,000-40,000  =  56,000)  to  the  40,000  gallons 
solution  of  0.24%  strength,  and  the  strength  will  be 
reduced  to  0.10%  strength. 

To  make  a  Definite  Volume  of  a  Weaker  Solution 
from  a  Stronger  Solution. — Suppose  it  is  desired  to 
make  60,000  gallons  solution  of  0.20%  strength  from  a 
solution  of  10%  strength: 

10 : 0.20 :  :  60,000 : X.    X  =  1200  gallons. 

Add  water  to  1200  gallons  of  the  solution  of  10% 
strength  until  the  whole  volume  reaches  60,000  gal- 
lons, and  the  60,000  gallons  will  have  a  0.20%  strength. 


26  THE   CYANIDE   PROCESS. 


Danger  in  working  the  Cyanide  Process. 

Potassium  cyanide  is  extremely  poisonous.  The 
building  in  which  cyaniding  is  carried  on,  or  in  which 
cyanide  solutions  are  standing,  should  be  well  ventilated. 
If  this  is  not  done,  the  men  suffer  from  headache, 
faintness,  and  dizziness.  It  is  recommended  *  that  the 
following  be  prepared  for  cyanide  poisoning: 

(1)  30  c.c.  of  23  per  cent,  solution  of  ferrous  sulphate. 

(2)  30  c.c.  of  5  per  cent,  solution  of  caustic  potash. 

(3)  2  grams  of  powdered  magnesium  oxide. 

(4)  A  metal  receptacle  of  1  pint  capacity. 

(5)  A  stomach- tube. 

Nos.  1  and  2  should  be  in  hermetically  sealed  tubes, 
which  can  be  broken  into  the  receptacle  and  powdered 
magnesia  and  half  a  pint  of  water  added,  shaken  up, 
and  administered.  This  amount  of  antidote  would 
account  for  5  grams  of  cyanide  of  potassium,  a  quantity 
far  in  excess  of  what  is  likely  to  be  drunk  accidentally, 
but,  to  secure  a  sufficiently  rapid  reaction,  the  ferrous 
sulphate  and  alkali  should  be  in  considerable  excess. 

F.  S.  Tuttle  recommends  the  swallowing  of  two  drops 
of  ammonia  on  a  lump  of  loaf  sugar;  for  external  poison-, 
ing  a  warm  bath  containing  washing-soda  and  common 
salt;  and  the  inhalation  of  ammonia,  when  fumes  are 
accidentally  inhaled. 


*  By  Dr.  C.  J.  Martin  and  Mr.  R.  A.  O'Brien,  Proceedings  of 
the  Society  of  Chemical  Industry  of  Victoria,  Vol.  I. 


THE  CHEMISTRY    OF    THE    CYANIDE    PROCESS.         27 


Methods  for  assaying  Cyanide  Solutions. 

One  cubic  centimeter  of  cyanide  solution  weighs 
approximately  1  gram  (1  cubic  centimeter  water  at 
4°  C.  weighs  1  gram).  By  dividing  the  number  of 
cubic  centimeters  solution  taken  by  the  weight  of  1 
assay-ton  (29.166  grams),  the  quotient  will  give  approx- 
imately the  number  of  assay-tons  taken.  This  makes 
it  easy  to  calculate  the  value  to  the  ton  of  solution. 
Seven  hundred  cubic  centimeters  of  solution  are  approxi- 
mately 24  assay-tons  (700-7-29.166  =  24).  When  the 
percentage  of  gold  in  the  solution  is  small,  1000  or 
2000  cubic  centimeters  solution  may  be  taken. 

1.  Take  1000  cubic  centimeters  solution,  add  excess 
of  copper  sulphate  (the  blue  or  green  color  of  the  filtrate 
indicates   excess).     Acidify   with   hydrochloric,    nitric, 
or  sulphuric  acid,  filter,  wash  precipitate,  and  scorify 
in  the  usual  way;   or  assay  by  crucible  method. 

2.  Put  500  cubic  centimeters  solution  into  a  casserole, 
put  under  a  hood  with  a  good  draft,  acidify  with  nitric 
acid,  boil  for  15  minutes,  then  add  J  gram  silver  dissolved 
in  nitric  acid,  filter,  and  assay  the  precipitate  and  filter- 
paper  as  above. 

3.  Put  1000  cubic  centimeters  solution  into  a  casserole 
or  enameled  iron  dish,  sprinkle  50  grams  litharge  into 
the  solution,  and  evaporate  to  dryness  on  a  sand-bath, 
water-bath,   or  iron    plate.     Scrape   out  the  residue, 
mix   with    7   grams    potassium   carbonate,    15   grams 
sodium  bicarbonate,  about  15  grams  silica  (powdered 
quartz  or  window-glass),  1  gram  wheat  flour,  put  into 


28  THE    CYANIDE   PROCESS. 

a  crucible,  cover  the  charge  with  about  8  grams  unfused 
powdered  borax,  and  assay  in  the  usual  way. 

The   litharge  must  be   sprinkled  into   the  solution 
before  evaporation  begins. 

4.  To  determine  both  Gold  and  Silver  in  a  Solution.— 
Precipitate  the  silver  with  a  solution  of  sodium  sul- 
phide, filter,  dry,  and  assay.     Precipitate  the  gold  in 
the  filtrate  by  zinc  chloride,  filter,  etc.,  and  assay. 

5.  Prepare  a  solution  of  mercuric  chloride,  and  keep 
it  in  a  glass-stoppered  bottle.    Take  a  measured  quantity 
of  gold-bearing  solution,  run  in,  from  a  burette,  mercuric- 
chloride  solution  in  excess;    until  no  further  precipi- 
tate is  produced.     Assay  the  precipitate. 

6.  Add    20    drops    potassium    bichromate    to    the 
measured  gold-bearing  solution.     Run  in  strong  silver 
nitrate  solution  until  the  deep-red  color  of  chromate 
of  silver  appears.     Add  100  grams  zinc  dust,  and  mix 
thoroughly.     Dissolve  the  remaining  zinc  by  sulphuric 
acid,  filter,  dry,  etc.,  and  assay. 

A.  F.  Cross  described  1  and  2  in  JL  Chem.  and 
Met.  Soc.  of  S.  Africa,  May,  1902.  In  "  Gaze's  Practi- 
cal Cyanide  Operations,"  5  and  6  are  described. 

7.  Pour  4  or  more  assay-tons  of  the  solution  to  be 
assayed  into  a  porcelain  dish  (casserole),  add  10  c.c. 
of  a  10%  solution  of  acetate  of  lead,  then  4  grams  of 
zinc  shavings,  boil  a  minute,  add  20  c.c.  of  hydro- 
chloric acid.     When  the  action  has  ceased,  boil  again, 
wash  the  spongy  lead  with  distilled  water,  transfer  it 
with  a  stirring-rod  to  a  piece  of  filter-paper,  squeeze 
into  a  compact  lump,  and  place  it  into  a  hot  cupel. 
The  mouth  of  the  muffle  should  contain  a  piece  of  dry  pine 


THE    CHEMISTRY    OF   THE   CYANIDE    PROCESS.         29 

wood  so  that  the  muffle  is  filled  with  flame  at  the  moment 
of  introducing  the  spongy  lead.     (Alfred  Chiddey.) 

8.  Take  3  to  10  assay- tons  of  the  solution,  according 
to  richness,  and  bring  to  boiling.     Acidify  with  hydro- 
chloric or  sulphuric  acid  to  strong  reaction  with  litmus 
paper.    At  end  of  2  or  3  minutes,  add  1  gram  copper 
sulphate  in  solution,  boil,  add  slight  excess  of  either 
sodium  or  potassium  sulphide  to  precipitate  the  copper. 
Continue  boiling  for  a  minute,  or  until  evolution  of 
hydrogen  sulphide  ceases.     Filter  through  an  eleven- 
centimeter  filter.     Remove  the  precipitate  adhering  to 
the  sides  of  the  casserole  by  a  little  cold  water  and 
rubbing.    Fold  filter,  burn  it  in  front  of  the  muffle  in  a 
2  J -inch  scorifier,  add  20  grams  test-lead,  a  small  amount 
of  borax,  and  scorify  to  8  or  9  grams.    (R.  Stuart  Browne.) 

9.  Draw  off  100  to  500  c.c.  of  the  cyanide  solution. 
Place  some  sawdust  or  porous  cotton  in  an  iron  pan 
or    any    convenient    iron    vessel.     Pour    the    solution 
gradually  upon  the  sawdust  and  allow  it  some  time  to 
be  absorbed  by  the  latter.     Apply  heat  gradually  to 
the  iron  vessel  until  all  the  solution  is  evaporated  and 
the  sawdust  reduced  to  carbon.    The  residue,  mixed 
with  the  proper  fluxes,  is  transferred  into  a  crucible,  and 
then  assayed  in  the  ordinary  way.    Should  the  volume 
be  too  large,  it  can  be  quartered  down.    (Robert  Grauer.) 

10.  Take  10  A.  T.  solution  and  heat  it  until  hot; 
add  ammoniacal  copper  nitrate  until  solution  shows 
permanent  blue  color;  add  carefully  excess  of  sulphuric 
acid  and  filter  immediately;  fold  filter-paper  and  burn 
in  a  scorifier;    transfer  to  a  crucible,  fuse  and  cupel. 
(Maurice  Lineman.) 


30  THE   CYANIDE   PROCESS. 

11.  Sometimes  it  is  desirable  to  know  approximately 
what  a  solution  carries,  before  one  of  the  above  tests 
can  be  made.  Acidify  with  sulphuric  acid,  add  excess 
of  silver  nitrate  (until  no  longer  a  precipitate  forms), 
filter  and  assay. 

When  t]ie  gold  only  is  to  be  determined,  it  is  best  to 
add  sufficient  silver  to  the  assay  charge  to  insure 
separation  of  the  button.  When  there  are  no  foreign 
substances  present,  as  sand,  etc.,  wash  the  precipitate 
of  gold  or  gold  and  silver  to  the  tip  of  the  filter,  dust 
about  2  grams  powdered  lead  over  the  inside  of  the 
wet  filter,  allow  to  drain,  fold  the  filter  to  as  small  a 
form  as  possible,  enclosing  the  precipitate  with  the 
folds,  bring  a  red-hot  cupel  in  front  of  the  muffle,  put  3 
grams  powdered  lead  into  the  cupel,  place  the  folded 
filter-paper  on  the  cupel,  and  allow  the  paper  to  burn 
at  a  low  temperature  in  front  of  the  muffle.  Then  cover 
the  ashes  with  about  3  grams  powdered  lead,  put  the 
cupel  into  the  muffle  and  cupel  as  usual.  The  silver  for 
separation  is  added  to  the  precipitate  before  folding 
the  filter,  when  gold  only  is  to  be  determined. 

Testing  Cyanide  Solutions  containing  Zinc.* 

i.  Total  Cyanide. — Add  excess  of  sodium  hydrate, 
2  or  3  drops  of  a  2%  potassium  iodide  solution,  and 
titrate  with  silver  nitrate  solution.  This  gives  the 
total  cyanide  (for  reference  below,  we  designate  the 


*  L.  W.  Green,  paper  read  before  the  Institute  of  Mining  and 
Metallurgy,  Oct.  17,  1901. 


THE    CHEMISTRY   OF   THE    CYANIDE   PROCESS.         31 

number  of  c.c.  of  silver  nitrate  solution  consumed  by 
Tc.c.). 

2.  Protective  Alkalinity.     (This  includes  the  alkaline 
hydrates,  NaOH,  KOH,  the   alkaline-earth    hydrates, 
mainly    Ca(OH)2,    and    half    the    monocarbonates    in 
solution.) — Add  excess  of  potassium  ferrocyanide,  twice 
the  amount  of  silver  nitrate  consumed  under  1,  a  few 
drops  of  phenolthalein  as  indicator,  and  titrate  with 
decinormal  nitric  acid.    The  amount  of  acid  used  will 
indicate  the  protective  alkalinity  (for  reference  as  above, 
we  designate  this  by  p).    The  ferrocyanide  precipitates 
the  zinc,  and  the  silver  the  cyanide.     These  precipitates 
may  be  filtered  off  before  titrating  with  the  acid. 

3.  Alkaline  Hydrates. — Add  excess  of  barium  chloride 
(until  no  further  precipitate  forms).    Then  proceed  as 
in  the  last  test.     (For  reference,  we  designate  this  by 
h).    Bicarbonates   may   be    determined   by   adding   a 
known  quantity  of  standard  alkali,  and  repeating  the 
above  test. 

4.  Total  Cyanide,  Ferrocyanide,  Sulphocyanides,  Chlo- 
rides, etc. — Add   amount  of   acid  (as   shown   by  2)  to 
neutralize  the  alkali,  a  drop  of  potassium  chromate, 
and  then  titrate  with  silver  nitrate  until  a  permanent 
faint- red  color  appears. 

5.  Ferrocyanides. — Add    10    c.c.  decinormal  sodium 
carbonate,  the  amount  of  silver  nitrate  consumed  under 
1,  and  shake  well.    All  the  ferrocyanide  present  will 
be  precipitated  by  the  zinc  in  the  solution,  and  any 
excess  of  zinc  will  be  thrown  down  as  basic  cabonate, 
and  there  will  be  an  excess  of  sodium  carbonate.    Add 
phenolphthalein  and  neutralize  slowly  with  decinormal 


32  THE    CYANIDE    PROCESS. 

nitric  acid.  Add  about  1  c.c.  more  of  the  nitric  acid, 
shake,  and  add  solution  of  sodium  carbonate  drop  by 
drop  till  the  clear  solution  is  just  faintly  pink.  Add 
excess  potassium  ferrocyanide.  The  reaction  between 
the  basic  zinc  carbonate  and  the  potassium  ferrocyanide 
makes  the  solution  strongly  alkaline.  Titrate  with 
decinormal  nitric  acid.  This  gives  the  amount  of  zinc 
less  what  has  been  precipitated  by  the  ferrocyanide 
originally  present  (S). 

6.  Zinc. — Add  sodium  carbonate  as  in  5,  and  amount 
silver  nitrate  consumed  in  4  to  precipitate  all  cyanides, 
ferrocyanides,  etc.,  which  precipitates  all  the  zinc  as 
basic  carbonate,  and  there  will  be  an  excess  of  sodium 
carbonate  in  the  solution.  Add  phenolphthalein  and 
neutralize  as  in  5.  Add  excess  potassium  ferrocya- 
nide and  titrate  with  decinormal  acid.  This  gives  the 
amount  of  zinc  (also  the  copper  and  cadmium,  if  these 
are  present)  (Z). 

If  in  each  of  these  tests  50  cubic  centimeters  of  the 
cyanide  solution  were  taken,  decinormal  nitric  acid 
used,  and  the  silver  nitrate  solution  contained  13.05 
grams  silver  nitrate  in  1000  cubic  centimeters  solution, 
the  following  are  the  factors : 

Total  cyanide  (as  KCN)  =  T  X 0.02% 

Protective  alkali  (as  KOH)         =pX0.0112% 
Alkaline  hydrate  (as  KOH)         -  h  X  0.01 12% 
Alkaline  carbonates  (as  K2C03)  =  (p-h)  X  0.0276% 
Ferrocyanide  (as  K4Fe(CN)6)     =  (Z  -S)  X 0.0351% 
Zinc  =  Zx0.0081% 


THE    CHEMISTRY    OF   THE    CYANIDE    PROCESS.         33 

One  cubic  centimeter  of  decinormal  potassium  ferro- 
cyanide  precipitates  0.75  c.c.  decinormal  zinc  solution 
from  dilute  neutral  solutions.  (Sufficiently  exact  for 
technical  purposes.) 

When  a  dilute  neutral  zinc  solution  is  precipitated 
by  excess  of  sodium  carbonate,  the  excess  of  alkali  being 
afterwards  neutralized  with  decinormal  acid,  a  precipi- 
tate of  basic  carbonate  of  almost  constant  composition 
is  obtained:  3Zn(OH)2,2ZnC03. 

Zinc  hydrate  or  carbonate  with  excess  of  potassium 
ferrocyanide  forms  zinc  ferrocyanide  and  potassium 
hydrate  or  carbonate : 

6Zn(OH)2+4K4Fe(CN)6 

=K4Fe(CN)6,3Zn2Fe(CN)6  +  12KOH, 

or 

6ZnC03+4K4Fe(CN)6 

=  K4Fe(CN)6,3Zn2Fe(CN)6  +  6K2C03. 

These  reactions  are  not  complete  until  the  alkali  is 
neutralized. 

Titrating  Complex  Solutions.  —  On  account  of  the 
impurities  in  solutions  that  have  been  used,  the  silver- 
nitrate  test  may  not  indicate  the  true  amount  of  cyanide 
in  solution.  For  such  solutions  J.  E.  Clennell  gives  the 
following  method:  "A  measured  volume  of  the  solution 
is  made  strongly  alkaline  by  the  addition  of  caustic 
potash  or  soda.  Sulphuretted  hydrogen  is  passed  into 
the  liquid  until  it  ceases  to  give  a  precipitate,  avoiding 
a  large  excess,  or,  what  is  better,  a  concentrated  solution 


34  THE   CYANIDE   PROCESS. 

of  pure  sodium  sulphide  is  added  in  slight  excess.  The 
solution  is  then  well  shaken  and  allowed  to  stand  until 
the  precipitate  has  subsided.  A  little  lime  may  be 
added  to  assist  the  settling  of  the  precipitate,  in  which 
case  it  can  be  filtered  without  difficulty  The  clear 
nitrate  is  freed  from  excess  of  sulphide  by  agitating 
with  litharge,  which  is  best  added  in  small  quantities  at 
a  time,  with  constant  agitation,  until  a  drop  of  the  liquid 
no  longer  gives  the  slightest  black  or  brown  coloration 
with  a  drop  of  lead  acetate  solution.  A  definite  volume 
is  then  filtered  off  and  tested  with  nitrate  of  silver  in 
the  ordinary  way."  (See  also  1  above,  under  Testing 
Cyanide  Solutions  containing  Zinc.) 


CHAPTER  IV. 

DETERMINING  THE  APPLICABILITY  OF  THE 
CYANIDE   PROCESS  TO  AN   ORE. 

LABORATORY  tests  are  made  to  determine  the  applica- 
bility of  the  cyanide  process  to  an  ore.  Laboratory 
tests,  of  course,  are  not  conclusive;  but,  if  they  are 
properly  conducted,  they  give  an  indication  of  what  may 
be  expected  on  a  large  scale.  Before  erecting  a  mill 
it  is  well  to  treat  50  to  100  Ibs.  ore  by  the  best  method 
as  indicated  by  the  laboratory  experiments,  which 
should  be  followed  by  treating  from  3  to  6  tons. 

The  percentage  of  extraction  is  usually  higher,  and 
the  consumption  of  cyanide  greater  in  laboratory  tests 
than  in  a  mill.  It  has  been  estimated  that  about  one- 
third  the  amount  of  potassium  cyanide  consumed  in 
laboratory  tests  is  consumed  in  mill-runs,  unless  the 
consumption  of  cyanide  is  due  to  "cyanicides."  By 
"cyanicides "  is  meant  those  substances  that  destroy 
the  potassium  cyanide,  as  free  acid  and  other  substances, 
some  of  which  are  mentioned  under  Interfering  Sub- 
stances (Chapter  11)7^ 

It  is  not  unusual  fo  get  a  higher  percentage  of  extrac- 
tion in  a  mill  than  in  the  laboratory. 

35 


36  THE   CYANIDE   PROCESS. 

A  chemical  analysis  of  the  ore  will  give  a  good  indica- 
tion as  to  what  preliminary  treatment  is  necessary. 

Extraction  Tests. 

1.  The  ore  is  crushed,  sampled,  and  assayed.* 

2.  The  ore  is  treated  for  interfering  substances,  such 
as  acid,  etc. 

3.  The  percentage  of  extraction  of  the  assay  value 
is  determined  on  samples  of  ore:   (1)  Crushed  to  differ- 
ent sizes;    (2)  in  contact  with  the  solution  for  different 
lengths  of  time;   (3)  for  different  strengths  of  solutions; 
(4)  by  different  methods  (percolation,  agitation,  etc.; 
roasted  ore,  dehydrated  ore,  etc.;   by  use  of  oxidizers, 
bromo-cyanogen,  etc.). 

After  the  ore  is  treated,  the  solution  is  filtered  off  and 
its  strength  determined,  and  the  ore  washed  and  assayed. 
The  difference  between  the  assay  value  before  treatment 
and  after  treatment  gives  the  extraction,  or  the  amount 
of  gold  in  the  solution  can  be  determined  by  one  of  the 
methods  given  under  the  Assay  of  Solutions  (Chapter 

in). 

Acidity. — Take  200  grams  ore,  cover  with  water, 
agitate  for  10  minutes,  filter,  wash,  and  titrate  with 
decinormal  potassium  hydrate  solution  (see  Appendix). 
Litmus  paper  may  be  used  as  an  indicator.  This  gives 
the  soluble  acidity. 

Run  an  excess  of  decinormal  potassium  hydrate 
solution,  from  a  burette,  on  the  residue,  agitate,  filter, 
wash,  and  titrate  back  with  decinormal  acid  solution. 

*  For  the  assay  of  ore  for  gold,  silver,  and  lead,  see  the  author's 
Manual  of  Assaying,  published  by  John  Wiley  &  Sons,  New  York. 


ITS    APPLICABILITY   TO    AN    ORE.  37 

This  gives  the  insoluble  acidity.  In  both  cases  the  ore 
must  be  washed  until  no  more  acid  can  be  washed  out, 
as  shown  by  litmus  indicator. 

Total  Acidity. — Take  200  grams  ore,  run  an  ex- 
cess of  decinormal  potassium  hydrate  solution,  from  a 
burette,  on  the  ore,  cover  the  ore  with  water,  agitate, 
filter,  and  wash  as  directed  above.  Add  litmus  solution 
to  the  filtrate  and  wash- water,  and  titrate  with  deci- 
normal sulphuric  acid  solution. 

Example. — Suppose  50  cubic  centimeters  decinormal 
potassium  hydrate  solution  was  run  on  the  ore,  and  it 
took  8  cubic  centimeters  of  the  decinormal  sulphuric 
acid  solution  to  neutralize  the  filtrate  and  wash-water. 
Then  it  took  42  cubic  centimeters  of  the  decinormal 
potassium  hydrate  solution  (50-8  =  42)  to  neutralize 
the  acid  in  200  grams  ore. 

One  cubic  centimeter  decinormal  potassium  hydrate 
solution  contains  0.0056  gram  potassium  hydrate. 
Having  taken  200  grams  ore,  each  cubic  centimeter 
decinormal  potassium  hydrate  solution  corresponds  to 
0.056  Ib.  potassium  hydrate  to  the  ton  (2000  Ibs.)  ore. 
(0.0056 -200  =  .000028.  2000 X. 000028  =  0.056.)  (If  42 
cubic  centimeters  potassium  hydrate  were  consumed, 
it  takes  .056x42  =  2.35  Ibs.) 

Assuming  that  the  acid  is  sulphuric  acid,  how  much 
slaked  lime  will  neutralize  the  acid  in  the  ore? 

2KOH  +  H2S04  =  K2S04  +  2H20 

(Potassium         (Sulphuric 

hydrate)  acid) 

112  98 

Ca(OH)2  +  H2S04  =  CaS04  +  2H20 

(Slaked  lime) 

74  98 


38  THE   CYANIDE   PROCESS. 

One  cubic  centimeter  decinormal  potassium  hydrate 
solution  corresponds  to  1  cubic  centimeter  decinormal 
sulphuric  acid  solution;  1  part  by  weight  potassium 
hydrate  (in  its  power  to  neutralize  sulphuric  acid) 
corresponds  to  0.66  part  slaked  lime  (74-^112  =  0.66). 
Hence,  in  the  example,  where  42  cubic  centimeters 
decinormal  potassium  hydrate  solution  were  consumed 
to  neutralize  the  acid  in  200  grams  ore,  it  takes  2.35  Ibs. 
potassium  hydrate,  or  1.55  Ibs.  slaked  lime,  to  the  ton 
ore  to  neutralize  the  acidity  of  the  ore  (0.056x42  =  2.35. 
2.35X0.66  =  1.55). 

To  neutralize  the  Acid  in  Ore  by  Commercial  Caustic 
Soda. — If  commercial  caustic  soda  is  to  be  used  to 
neutralize  the  acid  in  the  ore,  dissolve  10  grams  of  the 
soda  to  be  used  in  water,  and  dilute  to  1000  cubic 
centimeters.  Take  200  grams  ore,  cover  with  water, 
add  litmus  solution,  and  run  the  soda  solution,  from  a 
burette,  into  the  mixture  of  ore  and  water.  Stir  the 
ore  after  each  addition  of  solution.  Add  the  solution 
slowly  until  a  drop  gives  a  permanent  blue  color  to  the 
litmus  or  litmus  paper.  Each  cubic  centimeter  of  the 
caustic  soda  consumed  corresponds  to  0.1  Ib.  of  the 
same  soda  to  the  ton  (2000  Ibs.)  ore.  (In  1  cubic 
centimeter  of  the  solution  there  is  0.01  gram  soda. 
0.01  *  200  =  0.00005.  2000  X  .00005  =  0.1 .) 

Consumption  of  Cyanide. — Put  100  cubic  centi- 
meters of  a  0.25%  solution  of  potassium  cyanide  on 
200  grams  of  ore.  After  the  solution  has  been  in  con- 
tact with  the  ore  for  24  hours  (or  whatever  the  time 
may  be  for  the  experiment),  filter  off  10  cubic  centi- 
meters of  the  potassium  cyanide  solution,  and  titrate 


ITS   APPLICABILITY   TO   AN    ORE.  39 

it  with  the  decinormal  silver  nitrate  solution  (see  Chap- 
ter III). 

Example. — Suppose  the  potassium  cyanide  solution 
has  been  reduced  to  0.10%  strength.  This  shows  a 
consumption  of  1.5  Ibs.  potassium  cyanide  to  the  ton 
(2000  Ibs.)  ore.  (200  grams  ore  were  used,  and  only 
100  cubic  centimeters  solution.  200-100  =  2.  0.25- 
0.10=0.15.  0.15-2  =  0.075%.  2000  X. 00075  =  1.5.) 

By  running  a  blank  with  each  experiment,  that  is,  by 
allowing  the  same  amount  of  solution  and  of  the  same 
strength  to  stand  in  the  same  kind  of  container,  for  the 
same  length  of  time,  under  the  same  conditions  (except 
not  in  contact  with  ore),  etc.,  as  that  used  for  the 
experiment  with  the  ore,  the  loss  of  cyanide  not  due 
to  the  ore  may  be  found. 

In  making  the  tests  indicated  under  the  heading 
Extraction  Tests,  usually  200  grams  ore  are  put  into  a 
glass-stoppered  bottle  with  100  cubic  centimeters  of 
potassium  cyanide  solution  of  0.4%  or  0.5%  strength, 
and  shaken  for  20  minutes  or  longer.  Ten  cubic 
centimeters  of  the  solution  are  filtered  off  and  the 
strength  determined.  If  the  consumption  of  cyanide 
is  high,  the  ore  is  treated  for  "  cyanicides." 

Subsequent  experiments  are  carried  on  in  percola- 
tors, fitted  up  as  shown  in  Fig.  9.  A  filter  is  made  from 
asbestos  fiber,  over  which  is  placed  a  filter-paper,  and 
on  top  of  this  the  ore  is  placed;  or  an  iron-wire  gauze, 
supported  on  short  iron-wire  legs  and  covered  with 
duck  filter-cloth,  may  be  fitted  in  the  bottom.  Larger 
samples  can  be  treated  in  tubs,  in  barrels  sawed  in  two, 
etc.  These  should  be  fitted  with  false  bottoms  (Figs. 


40 


THE   CYANIDE   PROCESS. 


21-25),  covered  with  duck  filter-cloth.  When  wooden 
vessels  are  used,  they  should  be  coated  with  paraffin, 
asphalt,  or  coal-tar  paint. 


When  ore  is  crushed  to  pass  a  40-mesh  screen  or  finer, 
it  may  not  leach  in  the  percolators.  Fine  ore  can  bo 
treated  in  6-inch  ribbed  funnels,  Fig.  10. 


ITS    APPLICABILITY   TO    AN   ORE. 


41 


Precipitation  Tests.  —  The  solution  from-  the  tests 
can  be  passed  through  glass  tubes  rilled  with  zinc 
shavings;  or  if  larger  samples  are  treated,  a  small  zinc 


box  may  be  used  (Figs.  1  and  2).  The  amount  of  gold 
in  a  certain  number  of  cubic  centimeters  of  the  solu- 
tion is  determined  before  the  solution  is  passed  through 


42  THE    CYANIDE    PROCESS. 

the  zinc  shavings;  and  the  amount  of  gold  in  the  same 
number  of  cubic  centimeters  of  solution  is  determined 
after  the  solution  has  passed  through  the  zinc  shavings, 
by  one  of  the  methods  under  Methods  for  assaying 
Cyanide  Solutions.  From  these  results  the  percentage 
of  extraction  by  the  zinc  can  be  calculated. 

Small  portions  of  solution  may  be  evaporated  in 
dishes  made  from  lead-foil,  and  the  lead  folded  or 
rolled  up  and  cupelled;  but  this  usually  gives  too  low 
results. 

Coarse  gold  is  usually  amalgamated  with  mercury, 
as  it  takes  too  long  to  dissolve  it  with  cyanide  solu- 
tion. Ore  containing  coarse  gold  is  usually  crushed 
by  stamps  and  run  over  plates  amalgamated  with 
mercury;  and,  if  the  concentrate  or  tailing  contains 
sufficient  gold  to  pay  for  treatment,  it  may  be  treated 
by  the  cyanide  process  or  the  chlorination  process. 

Amalgamation  tests  can  be  made  by  shaking,  in  a 
bottle,  for  an  hour  or  two,  a  pound  of  ore  with  an 
ounce  of  clean  mercury  and  sufficient  water  to  make  a 
soft  mud.  Pan  out  the  mercury;  and  savo  the  tailing 
(and  concentrate,  if  any),  dry  it,  assay  it,  and,  if  it 
contains  sufficient  gold  to  pay  for  treatment,  make 
cyanide  tests  on  it  as  on  an  ore. 

Amalgamation  tests  can  also  be  made  by  panning 
the  ore  with  mercury  OP  by  running  the  ore  with  water 
over  an  amalgamated  plate. 


CHAPTER  V. 
NOTES. 

Strength  of  Solutions.— In  general,  use  the  weakest 
solution  that  gives  the  best  economical  results*)  The 
gold  is  precipitated  from  very  weak  solutions  by  elec- 
tricity, zinc  filaments,  or  the  lead-zinc  couple. 

Temperature. — The  rate  of  the  solution  of  gold 
increases  with  rise  of  temperature  until  a  maximum  is 
reached.  The  maximum  point  varies  with  solutions 
of  different  strengths.  The  rate  of  the  solution  of  other 
metallic  minerals  also  increases  with  the  rise  of  tempera- 
ture. Whether  it  is  profitable  or  not  to  apply  heat 
must  be  determined  for  each  ore?) 

Calcining — Ores  containing  hydrous  silicates  often 
yield  better  results  by  giving  them  a  preliminary  cal- 
cination at  a  temperature  not  exceeding  300°  F.  If  an 
ore  contains  lime  or  magnesia  carbonate,  and  it  is 
calcined  at  a  much  higher  temperature,  the  ore  will 
form  a  cement,  and  pack  when  the  solution  or  water 
is  applied.) 

Crushing. — For  porous  ore  coarse  crushing  is  usually 
best;  and  for  hard,  dense  ore  fine  crushing  must  be 
resorted  to.  At  the  Mercur  mine,  Utah,  ore  is  crushed 


44  THE    CYANIDE    PROCESS. 

to  \  to  J  inch;  and  at  the  Republic  mine,  Washington, 
ore  is  crushed  to  pass  a  120-mesh  screen.  It  should 
be  noted  that  a  laboratory  crushing  gives  a  coarser 
product  than  a  mill  crushing  through  the  same  size 
screen.  Laboratory  tests  are  usually  begun  on  ore 
crushed  to  pass  a  30-mesh  screeiO 
\N  Roasting. — When  ore'  is  roasted  for  the  purpose  of 
oxidizing  the  sulphur,  arsenic,  etc.,  the  roasting  should 
begin  at  a  low  temperature,  the  ore  should  be  stirred, 
air  admitted,  and  the  temperature  slowly  raised,  and 
finished  at  a  dull-red  heat.  The  ore  should  be  roasted 
"dead,"  or  "sweet."  The  roasting  may  produce 
soluble  salts,  which  should  be  washed  out  of  the  ore 
before  the  cyanide  solution  is  applied.  The  wash-water 
will  contain  some  values,  which  can  be  recovered  by 
precipitation/) 

Difficulties  in  the  precipitation  by  Zinc. — One  of 
these  difficulties  is  the  appearance  of  a  white  incrusta- 
tion said  to  consist  of  zinc  ferrocyanide,  which  covers 
the  zinc  shavings  and  prevents  further  action.  This 
does  not  appear  when  much  free  potassium  cyanide  or 
alkali  is  present.  Formation  of  zinc  ferrocyanide  is 
increased  by  soluble  salts  of  iron  in  the  solution. 

Used  Solutions  Less  Powerful  than  Fresh  Solutions  of 
the  Same  Strength. — Alfred  James  found  by  experi- 
ment that  the  addition  of  lime  to  used  solutions  improved 
the  extraction  from  free  gold  ores  having  a  quartz 
gangue,  but  had  the  opposite  effect  on  Dre  containing 
sulphur.  /  In  the  latter  case  he  found  the  addition  of 
sodium  sulphide  (avoid  excess),  followed  by  the  addi- 
tion of  a  small  amount  of  lead  salt  (acetate  or  chloride) 


NOTES,  45 

to  be  effective.    After  such  additions,  time 
must  be  allowed  for  precipitates  to  settle. 

He  also  showed  that  the  potassium-zinc  oxide  in  the 
used  solution  combines  with  freshly  added  cyanide, 
which  results  in  a  weaker  solution  than  the  chemist  had 
intended  to  make: 

K2Zn02 + 4KCN  +  2H20 = K2Zn(CN)  4 + 4KOH. 

The  accumulation  of  zinc  in  the  solution  is  prevented 
by  the  action  of  the  sulphides  in  the  ore,  or  by  the  above- 
described  treatment. 

By  the  precipitation  of  gold  from  cyanide  solution 
by  zinc,  a  double  cyanide  of  potassium  and  zinc, 
K2Zn(CN)4,  is  formed.  A  solution  of  K2Zn(CN)4  dis- 
solves gold,  but  more  satisfactory  results  are  obtained 
by  removing  the  zinc  by  the  above  treatment. 

W.  H.  Davis  has  patented  a  process  for  "regenera- 
tion of  the  cyanide  in  the  solution  and  clarifying  of 
the  latter"  by  "  introducing  into  the  solution  an  alka- 
line hydrate  and  then  subjecting  the  mixture. to  the 
action  of  an  alternating  electric  current." 

Silver  Ores. — As  a  general  rule,  potassium  cyanide 
does  not  extract  a  very  large  percentage  of  silver  from 
ore,  under  the  same  conditions  that  it  extracts  a  large 
percentage  of  the  gold.  When  the  silver  is  in  the  ore 
as  a  chloride,  bromide,  or  iodide,  the  extraction  is  high : 

AgCl + 2KCN  =  KAg(CN2)  +  KC1. 

The  reactions  for  the  silver  bromide  and  silver  iodide 
are  similar.  No  oxygen  is  needed  to  effect  the  solution 
of  silver,  when  it  is  in  the  ore  as  a  compound.  When 


46  THE, CYANIDE   PROCESS. 

the  silver  is  combined  with  sulphur,  arsenic,  etc.,  the 
extraction  is  low,  which  is  probably  partly  due  to  the 
formation  of  potassium  sulphide: 

Ag2S + 4KCN = 2KAg(CN)  2 + K2S. 

When  such  ore  is  roasted  with  from  0.25%  to  15% 
common  salt,  a  silver  chloride  forms,  which  is  soluble 
in  potassium  cyanide.  Add  the  salt  near  the  end  of 
the  roasting. 

Low-grade  ores  containing  both  gold  and  silver  may 
be  profitably  treated  by  this  method.  Ores  running 
high  in  silver  can  be  more  profitably  treated  by  other 
methods,  as  much  potassium  cyanide  is  consumed  in 
the  solution  of  silver  chloride. 

If  roasted,  the  ore  may  need  a  preliminary  water- 
wash  to  clean  the  ore  of  soluble  salts.  Some  values 
will  also  wash  out,  which  can  be  recovered  by  precipitat- 
ing them. 

Ore  of  the  Dos  Cabezas  mines  *  of  Sonora,  Mexico, 
assaying  29  ounces  silver  and  0.1  ounce  gold,  by  com- 
plete sliming,  and  treating  for  24  hours  by  agitation  by 
compressed  air,  the  solution  being  warmed,  the  tailing 
assayed  trace  of  silver  and  no  gold.  Consumption  of 
potassium  cyanide,  7.3  pounds  per  ton  of  ore  treated. 

The  Clean-up. — At  the  end  of  two  weeks  or  a  month, 
the  precipitates  in  the  zinc-boxes  are  collected,  and 
turned  into  bullion.  These  precipitates,  in  addition  to 
the  gold  and  silver,  often  contain  lead,  zinc,  iron,  lime, 
copper,  etc.;  and,  even  if  they  contain  no  copper,  lead, 

*  M.  B.  Parker  in  the  Bulletin  of  the  International  Miners'  Asso- 
ciation. 


NOTES.  47 

etc.,  they  contain  pieces  of  partly  used  up  zinc.  The 
coarse  zinc  is  usually  sieved  off,  and  put  back  into  the 
zinc-boxes.  The  liquid  is  pumped  or  siphoned  off  the 
gold  slimes,  and  they  are  dried;  or  they  are  filter- 
pressed  and  then  dried. 

In  cleaning  up,  the  zinc  shavings  should  be  exposed 
to  the  air  as  little  as  possible,  as  they  oxidize  rapidly, 
after  which  they  are  almost  useless  for  precipitation. 

There  are  several  methods  by  which  these  slimes  are 
treated :  (1)  They  may  be  melted  with  borax;  (2)  roasted, 
then  melted ;  (3)  treated  with  sulphuric  acid,  then  melted ; 
(4)  treated  with  nitric  acid,  then  melted.  Alfred 
James  found  that  (2),  (3)_,  (4)  occasioned  an  additional 
loss  to  that  sustained  by  melting  with  borax  only, 
and  that  treatment  with  sulphuric  acid,  then  melting, 
sustained  the  least  loss  among  the  three.  His  advice 
is  to  handle  the  gold  slimes  as  little  as  possible,  and  to 
use  lead-free  zinc  in  the  precipitation.  The  losses,  in 
cleaning  up,  have  been  reduced  by  the  use  of  a  special 
filter- press. 

Lead  Smelting  of  Zinc-Gold  Slimes.— P.  S.  Tavener  * 
found  that  by  fusing  the  precipitates  with  litharge,  as 
in  an  assay,  more  can  be  recovered  than  by  the  roast- 
ing and  acid  treatment.  By  this  process  the  zinc 
slimes  are  dried,  roughly  weighed  to  determine  the 
amount  of  fluxes  necessary,  smelted  in  a  reverberatory 
furnace  with  the  fluxes  and  the  gold-lead  cupelled. 
The  charge  by  weight  is  approximately  as  follows: 


*  Journal  of  the    Chemical  and   Metallurgical   Society  of  South 
Africa,  October,  1902. 


48  THE    CYANIDE    PROCESS. 

Zinc  slimes 100  parts 

Litharge 60     " 

Assay  slag 10  to     15     " 

Foul  slag. 10  "      15     " 

Silica 5  "     10    " 

Charge  for  fine  zinc: 

Fine  zinc 100  parts 

Litharge 150     " 

Slag 20    " 

Sawdust  is  used  as  a  reducing  agent.  One  per  cent, 
of  the  weight  of  the  litharge  of  sawdust  is  mixed  with 
the  slime.  If  the  proportion  of  litharge  is  in  excess 
of  60  per  cent.,  1.5  to  2  per  cent,  of  sawdust  is  required. 
No  sawdust  is  added  to  the  fine  zinc.  To  determine  the 
amount  of  slag  necessary  to  produce  a  fusible  slag, 
trials  can  be  made  in  a  crucible  with  a  small  quantity 
of  slime  or  fine  zinc.  It  takes  about  30  per  cent,  less 
slag  to  make  a  fusible  slag  in  the  furnace  than  in  the 
crucible.  The  resulting  lead  should  not  contain  more 
than  about  8  per  cent,  of  gold,  and  10  per  cent,  is  the 
limit. 

Additional  Notes. 

1.  Lime  is  used  to  settle  slimes. 

2.  Lime  is  preferred  to  soda  for  neutralizing  acidity, 
as  it  does  not  cause  formation  of  zinc  ferrocyanide, 
which  impairs  the  activity  of  zinc  for  precipitation. 

3.  If  the  solution  is  not  clear,  contains  suspended 
matter,  pass  it  through,  .a  sand  filter  before  entering  the 
zinc-boxes. 


NOTES.  49 

4.  The  formation  of  hydrogen  gas  in  the  zinc-boxes 
is  caused  by  the  action  of  potassium  hydrate  on  the 
zinc.     Excess  of  caustic  soda  or  lime  used  in  neutralizing 
the  ore,  if  not  washed  out,  will  act  on  the  zinc. 

5.  The   solutions   used   on   ores   containing  no   sul- 
phides are  kept  slightly  alkaline.     "Add  soda  or  lime, 
a  little  at  a  time,  till  the  solution  flowing  out  from  the 
extractor-boxes  does  not  rise  in  cyanide  test."     (James.) 

Excess  of  alkali  is  to  be  avoided  with  sulphide  ores. 
"A  little  soda  is  necessary,  and  helps  the  zinc-box 
reaction,  but  use  lime  generally  for  neutralizing  purposes, 
and  keep  your  solutions  so  that  they  rise  apparently  in 
cyanide,  if  soda  is  added."  (" Cyanide  Practice  by 
James.") 

7.  Sampling  tailings  in  a  vat  by  a  glass  tube  or  iron 
pipe  may  result  in  not  getting  a  fair  sample  of  the 
bottom  layer. 

8.  From  \  to  1  Ib.  cyanide  is  consumed  per  ton  of  ore 
treated.    Some  pyritic  ores  consume  from  3  to  50  Ibs. 

9.  From   \  to  \  Ib.  zinc  is  consumed  per  ton  ore 
treated. 

10.  One  Ib.  zinc  should  precipitate  about  6  Ibs.  gold, 
but  in  practice  it  takes  from  5  oz.  to  1  Ib.  zinc  to  pre- 
cipitate 1  oz.  gold.     Compounds  in  the  solution,  formed 
by  the  solution  and  the  minerals  in  the  ore,  are,  in  a 
large  measure,  the  cause  of  the  high  consumption  of 
zinc. 

11.  Iron  in  contact  with  zinc  causes  solution  of  the 
zinc.    The  use  of  iron  trays  cannot  be  avoided. 

12.  Zinc  shavings  weigh  about  5  Ibs.  per  cubic  foot 
in  the  boxes. 


50  THE  CYANIDE   PROCESS. 

13.  There  should   be  three  zinc-boxes  in  a  cyanide 
works — one    for    the    strong    solution,    one    for   weak 
solutions,  and  one  for  the  washings. 

14.  Solutions  rich  in  gold  give  a  cleaner  deposit  on 
the  zinc  with  less  consumption  of  cyanide,  the  volume 
passing  through  the  precipitation-boxes  being  less. 

15.  Most  of  the  gold  is  precipitated  in  the  upper  com- 
partments of  the  zinc-box.    The  zinc  dissolves  more 
rapidly  in  the  upper  compartments.    As  the  precipi- 
tation proceeds,  the  zinc  is  transferred  from  the  lower 
compartments  to  the  upper  ones,   and  fresh  zinc  is 
added  at  the  foot  of  the  box. 

16.  There  are  usually  about  ten  compartments  in  a 
zinc-box,  and  the  box  has  a  fall  of  about  3?  inches. 
The  first  and  last  compartments  are  usually  left  empty 
or  supplied  with  sand  filters  to  clarify  the  solution. 

17.  The  surface  of  a  charge  of  ore  should  be  about 
12  inches  below  the  rim  of  the  vat,  and  the  solution 
about  3  inches  above  the  ore. 

18.  Wooden  vats  should  be   coated  with  paraffin, 
asphalt,  or  coal-tar  paint. 

19.  A  stock  or  strong  solution  is  not  made  until 
wanted,  as  it  undergoes  somewhat  rapid  decomposition. 

20.  Gold  can  not  be  precipitated  by  zinc  shavings 
from  a  cyanide  solution  which  does  not  contain  at 
least  2  Ibs.  potassium   cyanide    to   the  ton  solution. 
When  the  solution  contains  less  than  0.05  per  cent. 
KCN,  the  solution  must  be  in  contact  with  the  zinc  for 
an  hour. 

21.  Zinc  shavings  used  in  the  precipitation  of  gold 
from  cyanide  solutions  will  weigh  about  6.5  to  7  Ibs. 


NOTES.  51 

per  cubic  foot  when  well  packed.  It  has  been  found 
advantageous  to  pack  the  precipitation  boxes  closely 
and  firmly,  as  this  offers  a  greater  surface  of  zinc  to  the 
passing  solutions  than  where  they  are  loosely  packed. 

22.  Foaming  in  the  zinc  boxes  is  due  to  excessive 
alkalinity. 

23.  Some  commercial  cyanide  contains  soluble  sul- 
phides, which  should  be  removed  by  adding  to  the 
solution  some  slaked  lime,  and  a  requisite  amount  of  lead 
salt  (acetate  or  chloride).     Filter  the  solution,  or  allow 
the  precipitate  to  settle  and  decant  the  clear  solution. 

24.  If  a  solution  contains  any  reducing  agents,  these 
should  be  removed  or  oxidized  before  the  solution  is 
applied  to  the  ore. 

Useful  Information. 

It  takes  about  700  Ibs.  solution  to  saturate  and  cover 
1  ton  of  ore. 

It  requires  100  gallons  water  to  sluice  1  ton  tailings 
out  of  a  vat. 

22  to  28  cubic  feet  =  l  ton  dry  raw  ore. 

20  to  26  cubic  feet  =  1  ton  ore  wetted  down. 

18  cubic  feet  of  earth  =  1  ton. 

1  cubic  foot  of  quartz  in  place  =  165  Ibs. 

1  cubic  foot  of  quartz  broken  =  94  Ibs. 

13  cubic  feet  quartz,  unbroken  =  1  ton. 

1  cubic  foot  of  water  contains  7J  gallons  and  weighs 
62J  Ibs. 

To  find  the  capacity  of  a  tank  in  cubic  feet,  square 
the  diameter  of  the  bottom  in  feet,  multiply  by  0.7854, 
and  multiply  the  product  by  the  inside  height  in  feet. 


CHAPTER  VI. 

SHORT  DESCRIPTIONS  OF  SOME  CYANIDE 
PROCESSES. 

ALL  the  cyanide  processes,  with  perhaps  one  or  two 
exceptions,  are  covered  by  patent.  The  patent  is  on 
the  method  of  operating  or  on  the  method  of  precipita- 
ting, or  both. 

The  United  States  District  Court  for  Idaho  decided 
(in  1901)  against  the  patent  on  zinc  dust  for  precipitating 
gold-cyanide  solutions,  holding  that  the  same  had  been 
anticipated  by  prior  publications  and  patents.  The 
case  may  be  carried  to  a  higher  court  for  final  decision. 

McArthur-Forrest  Process. — This  process  consists  in 
applying  dilute  solutions  of  potassium  cyanide  to  ore 
(not  exceeding  8  parts  of  cyanogen  to  1000  parts  of 
water),  and  precipitating  the  gold  from  the  solution  by 
means  of  zinc  shavings.  The  zinc  shavings  "are  cut 
by  a  turning-tool  from  a  series  of  zinc  disks  held  between 
lathe-centers  and  turned."  The  patent  also  covers  the 
use  of  an  alkali  or  alkaline  earth  to  neutralize  the 
acidity  of  the  ore. 

Siemens-Halske  Process. — By  this  process  the  gold  is 
precipitated  from  the  solution  by  electricity.  The 
anodes  are  iron  plates,  7x3xJ  in.  thick,  covered  with 
canvas  to  prevent  short  circuits.  The  cathodes  are 

52 


SHORT  DESCRIPTIONS   OF   SOME   PROCESSES. 


53 


very  thin  lead  sheets,  stretched  between  two  iron  wires, 
and  fastened  (3  in  each)  in  light  wooden  frames,  2x3  ft., 
which  are  suspended  between  the  iron  plates.  The 
iron  anodes  cause  the  formation  of  Prussian  blue  by 
the  reaction  of  ferrocyanide  with  iron  oxide. 


HAMPTON  ZINC  LATHE 


FIG.  11. — Hampton  (Patent)  Zinc  Lathe. 

Sometimes  the  space  between  the  iron  plates  is  filled 
with  lead  shavings,  which  take  the  place  of  the  lead 
sheets,  and  offer  a  larger  surface. 


54  THE    CYANIDE   PROCESS. 

By  this  method  of  precipitation  very  weak  solutions  of 
potassium  cyanide  can  be  used  to  leach  the  ore.  By 
employing  very  weak  solutions  of  potassium  cyanide, 
less  cyanide  is  lost  by  "cyanicides,"  and  in  the  solu- 
tion that  always  remains  in  the  ore;  but  it  requires  a 
longer  contact  of  the  solution  with  the  ore. 
I  The  Pneumatic  Cyanide  Process. — After  the  cyanide 
solution  has  been  put  on  the  ore,  compressed  air  is 
turned  into  the  space  beneath  the  false  bottom  in  the 
vat,  and  is  evenly  distributed  by  means  of  a  coil  of 
perforated  pipes.  The  air  forces  its  way  through  every 
hole  in  the  perforated  false  bottom,  keeps  the  ore 
agitated,  and  supplies  the  oxygen  for  the  rapid  solu- 
tion of  the  gold.  It  is  claimed  that  nearly  all  sulphide 
ores,  except  those  containing  an  excess  of  copper  and 
antimony,  can  be  profitably  treated  by  this  process. 
It  admits  of  finer  crushing,  and  requires  less  time  of 
contact,  than  the  ordinary  percolation  method.  The 
slimes  are  forced,  by  the  compressed  air,  to  the  surface, 
leaving  the  coarser  and  heavier  portions  of  the  ore  on 
the  filter,  which  facilitates  the  leaching.  \ 

The  Betty  Cyanide  Process. — This  process  effects  the 
precipitation  of  gold  from  weak  solutions.  The  zinc 
shavings  are  completely  covered  with  a  coat  of  lead 
by  being  moved  about  in  a  10%  solution  of  lead  acetate. 
When  the  coating  is  complete,  they  are  immediately 
transferred  to  the  precipitation- tank,  avoiding  contact 
with  the  air.  The  gold  is  precipitated  on  the  lead  of 
this  lead-zinc  couple.  This  lead-zinc  loses  its  precipita- 
ting power  in  the  first  compartment  after  a  ten  days' 
run,  when  it  should  be  replaced  by  freshly  prepared 


SHORT  DESCRIPTIONS   OF    SOME   PROCESSES.          55 

zinc,  and  used  to  precipitate  gold  from  solutions  stronger 
in  cyanide. 
The  precipitating-tank  is  25  feet  long,  6  feet  wide, 


FIG.  12. — Arrangement  of  Pneumatic  Air-pipe,  arranged  above 
false  bottom  of  Leaching-tank.  This  illustrates  the  most  simple 
pipe  arrangement  of  the  "Pneumatic"  Process,  but  sometimes  it 
is  preferred  to  lead  the  main  supply-pipe  over  the  top  of  the  Leach- 
ing-tanks,  arrange  the  air-pipe  in  sections  and  connect  same  by 
different  drop-pipes. 

and  5  feet  deep,  divided  into  five  compartments.  Four- 
teen to  fifteen  tons  of  solution  can  be  treated  hourly. 
The  solution  enters  the  precipitating-tank  at  the  top. 


56 


THE    CYANIDE   PROCESS. 


SHORT  DESCRIPTIONS    OF    SOME    PROCESSES.          57 


With  the  gold-bearing  solution,  75  gallons  of  a 
cyanide  solution  is  allowed  to  run  freely  for  four  hours 
into  the  tank,  bringing  the  solution  up  from  0.007% 
to  0.025%;  75  gallons  of  1J%  cyanide  solution  are  now 
run  in  for  6  hours.  About  12  hours  after  this,  a  small 
piece  of  cyanide  is  occasionally  dropped  into  the  gold- 
bearing  solution,  to  keep  the  strength  up  to  about 
0.008  per  cent. 

The  Godbe  Agitation  Process.  —  Generally,  the  finer 
an  ore  is  pulverized,  the  higher  the  percentage  of  extrac- 
tion. But  fine  ore  packs,  which  interferes  with  the 
leaching,  and  a  considerable  amount  of  the  gold-bearing 
solution  cannot  be  washed  out  of  the  ore. 

The  difficulties  of  leaching  slimes  are  overcome  by 
introducing  the  cyanide  solution,  containing  lime, 
below  the  false  filter-bottom,  agitating  the  ore  by  stirrers 
or  compressed  air,  and  displacing  the  solution  by  run- 
ning the  second  solution  in  from  the  bottom,  which  is 
displaced  in  the  same  way  by  water.  It  takes  about 
two  displacements  by  the  weaker  solution,  followed 
by  a  water-  wash,  to  wash  all  the  values  out.  Agita- 
tion increases  the  extraction. 

The  ore  may  be  crushed  wet,  run  into  the  vats,  and 
the  water  displaced  by  the  cyanide  solution.  By  using 
a  large  amount  of  solution,  a  weaker  solution  of  potas- 
sium cyanide  can  be  used,  and  the  proper  strength  of 
the  solution  can  be  kept  in  constant  contact  with  the 
ore  by  continuous  upward  percolation. 

The  Begeer  Cyanide  Process.  —  This  process  differs 
from  other  processes  in  running  the  cyanide  solution, 
before  using,  repeatedly  through  a  centrifugal  pump 


53  THE   CYANIDE    PROCESS. 

which  has  air  connections.  In  this  way  the  solution 
is  saturated  with  oxygen,  and,  it  is  claimed,  will  dissolve 
a  higher  percentage  of  gold  and  silver  in  a  shorter  time 
than  a  solution  not  so  treated.  The  power  required  for 
this  purpose  is  about  one-third  H.P.  for  100-ton  plant. 

The  Decantation  Process. — Slimes  are  treated  by  this 
process.  The  slimes  are  agitated  until  the  gold  is 
dissolved,  when  they  are  allowed  to  settle,  and  the 
clear  solution  is  drawn  off  from  the  top  of  the  tank, 
and  run  through  the  precipitating-boxes.  The  slimes 
are  washed  several  times  with  a  repetition  of  agitation, 
settling,  and  drawing  off  of  the  clear  solution.  Some- 
times the  slimes  are  agitated  by  a  centrifugal  pump 
attached  to  the  bottom  of  the  tank  (see  Fig.  8). 

Precipitation  by  Zinc  Dust. — At  the  Golden  Gate 
mill,  Mercur,  Utah,  zinc  dust  is  used  to  precipitate  the 
gold  from  the  cyanide  solution.  The  zinc  dust  used  is 
a  blue  bowder,  the  by-product  from  zinc  smelting. 
Thirty  tons  of  solution  is  pumped  into  a  precipitating- 
tank;  and,  while  the  tank  is  filling,  the  precipitate  from 
former  precipitations,  which  contains  unconsumed  zinc 
dust,  is  stirred  up  by  introducing  air  into  the  bottom 
of  the  tank  through  a  pipe,  at  10  to  15  Ibs.  pressure. 
Five  Ibs.  fresh  zinc  dust  is  used  for  30  tons  solution. 
Beginning  when  the  tank  is  half  full,  the  zinc  dust  is 
sieved  into  the  solution,  at  intervals,  until  all  the  zinc 
is  added.  The  sediment  is  then  thoroughly  stirred  up 
by  moving  the  air-pipe  about  the  bottom,  after  which 
the  pipe  is  removed,  and  the  precipitate  allowed  to 
settle  for  half  an  hour.  The  liquid  is  then  drawn  off 
through  an  opening  in  the  side  of  the  tank,,  about  8 


SHORT    DESCRIPTIONS    OF    SOME    PROCESSES.  59 

inches  above  the  bottom,  and  passed  through  the  filter- 
presses.  The  precipitation  is  rapid.  About  1J  Ibs.  zinc 
dust  is  consumed  per  ounce  of  gold  recovered. 

At  the  Republic  mill,  Washington,  twenty  tons  of 
solution  are  precipitated  at  each  charge  by  sifting  in 
the  necessary  quantity  of  zinc  dust,  while  the  solution 
is  being  agitated  by  means  of  compressed  air,  intro- 
duced through  a  pipe  into  the  bottom  of  the  tank. 
About  1.25  Ibs.  zinc  dust  is  consumed  per  ounce  gold 
precipitated,  or  0.80  Ib.  per  ounce  combined  gold  and 
silver. 

The  Bromo-Cyanogen  Process. — This  process  consists 
in  using  a  mixture  of  cyanogen  bromide  and  potassium 
cyanide.  It  is  the  Sulman-Teed  process,  known  in 
some  places  as  the  "Diehl": 

CNBr   +  3KCN   +  2Au  =  2KAu(CN)2  +  KBr 

(Cyanogen         (Potassium         (Gold)  (Potassium-  (Potasssium 

bromide)  cyanide)  gold  cyanide)  bromide) 

It  will  be  noticed  that  by  this  process  no  oxygen  is 
necessary  to  dissolve  the  gold. 

At  Deloro,  Canada,  the  mixture  of  potassium  cyanide 
and  cyanogen  bromide  solution  is  run  on  the  concentrates 
to  the  amount  of  about  one-third  of  the  weight  of  the 
ore.  The  circulating  method  is  used.  The  solution 
percolates  through  the  ore,  is  brought  up  to  strength 
and  kept  in  continued  circulation  for  24  hours,  then  the 
ore  is  drained,  turned  over  by  shoveling,  and  the  cir- 
culation continued  until  assays  show  the  extraction 
complete.  The  ore  is  then  given  a  wash  by  a  weak 
cyanide  solution,  followed  by  a  water- wash.  Consump- 
tion per  ton  of  concentrates:  Potassium  cyanide,  2  Ibs.; 


60  THE   CYANIDE    PROCESS. 

cyanogea  bromide,  0.5  lb.;  zinc  dust  (precipitation), 
0.19  lb.;  treatment,  80  to  100  hours;  extraction,  87% 
to  94%. 

The  strength  of  the  potassium  cyanide  is  found  by 
the  silver  nitrate  test.  To  find  the  amount  of  cyanogen 
bromide,  acidify  by  hydrochloric  acid,  add  slight  excess 
of  potassium  iodide,  starch  solution  as  indicator,  and 
titrate  the  liberated  iodine  by  decinormal  sodium 
thiosulphate.  One  cubic  centimeter  decinormal  thio- 
sulphate  corresponds  to  0.0052  gram  cyanogen  bromide: 

BrCN  +  2KI  +  2HC1  =  BrCN  +  2HI  +  2KC1, 

BrCN  +  2HI  =  HBr  +  HCN  + 12, 

2Na2S203  +  I2  =  2NaI  4  Na2S4O6. 

Excess  of  bromo-cyanogen  should  be  avoided,  as  it  is 
no  longer  operative  after  passing  the  zinc  boxes.  The 
amount  of  cyanogen  bromide  should  not  be  greater 
than  25%  of  the  potassium  cyanide  present  in  the 
regular  solution. 

The  Holderman  Method  of  extracting  Gold  by  Cyanide. 
— The  main  feature  of  this  method  is  the  Holderman 
patented  filter-tank,  having  its  sides  and  ends,  as  well 
as  its  bottom,  covered  with  filter  material,  stretched 
over  A-shaped  slats,  giving  a  percolating  and  leaching 
area  equal  to  the  whole  surface  of  the  interior  of  the 
tank.  The  bottom  of  the  tank  slopes  from  back  to 
front,  allowing  an  easy  discharge  of  treated  ore  through 
several  front  gates.  The  tanks  are  about  5x7x12  feet 
in  dimensions.  About  three  of  these  tanks  are  arranged 
in  stair-like  succession,  which  constitutes  a  plant  for 
the  treatment  of  ore.  The  uppermost  tank  is  provided 


SHORT   DESCRIPTIONS   OF    SOME   PROCESSES.  61 

with  an  agitator.  In  this  tank  the  ore  is  treated  with 
cyanide  solution  for  from  2  to  6  hours.  At  the  end 
of  this  time  the  solution  is  drawn  off  through  the  filter, 
the  agitator  being  kept  in  motion,  and  the  ore  is  then 
washed  into  the  next  lower  tank  with  a  weak  cyanide 
solution,  and  allowed  to  stand  a  certain  length  of  time, 
then  the  solution  is  drawn  off  through  the  filter,  and 
the  ore  washed  into  the  next  lower  tank. 

The  Moore  Process. — This  process  employs  a  peculiar 
hollow  truncated  cone  revolving  on  a  horizontal  axis 
in  which  the  ore  is  treated  with  cyanide  solution,  agitated, 
aerated,  and  the  sand  is  separated  from  the  slime.  The 
slime  with  the  solution  flows  down  inclined  troughs  into 
agitation-tanks.  Agitation  is  accomplished  by  a  centrif- 
ugal sand-pump,  and  the  slime  is  finally  filter-pressed. 

The  Hendryx  Process. — This  process  is  designed  for 
the  rapid  extraction  of  gold,  silver,  and  other  metals 
from  their  natural  ores. 

The  Process. — The  ore  is  first  crushed  in  a  weak 
chemical  solution  containing  one-fiftieth  of  one  per  cent., 
or  less,  of  cyanide  of  potassium,  and  the  pulp  passed 
over  amalgamated  copper  plates;  then  the  ore-pulp 
solution  is  agitated  in  the  Hendryx  Agitator,  in  which 
the  gold  and  silver  from  the  ore  pulp  is  dissolved  and 
precipitated  by  either  electricity  or  zinc. 

The  solutions  are  now  removed  and  returned  to 
a  subsidiary  tank  on  their  way  to  the  storage-tank, 
hereinafter  designated  as  " battery  storage/'  from  which 
the  crushing  and  grinding  machinery  is  supplied,  an 
additional  set  of  plates  for  electrical  deposition  is 
installed.  (Fig.  15.) 


62 


SHORT  DESCRIPTIONS   OF  SOME  PROCESSES. 


OF  THE 

UNIVERSITY 

OF 


THE   CYANIDE 


63 


64  THE   CYANIDE    PROCESS. 

In  the  event  of  there  being  values  left  in  the  puip, 
owing  to  insoluble  metallic  compounds  or  alloys,  or 
owing  to  the  lack  of  having  ground  the  ore  sufficiently 
fine  to  permit  of  the  solutions  coming  in  contact  with 
the  metals,  then  a  further  step  in  the  process  is  carried 
out,  consisting  of  concentration  (tables  being  shown  in 
Figs.  14  and  15). 

The  Hendryx  Agitator  (see  Fig.  16)  is  designed  for 
the  rapid  extraction  of  gold  and  silver  from  unsepa- 
rated  sands  and  slimes  by  means  of  agitation  and 
aeration  in  weak  chemical  solutions  containing  cyanide 
of  potassium  or  sodium.  Simultaneously  the  values 
are  deposited  on  plates  by  electricity,  cyanide  is  regen- 
erated, and  the  fouling  of  the  solutions  is  prevented. 

Essential  Mechanical  Feature. — The  essential  mechan- 
ical feature  of  the  Agitator  (Fig.  16)  consists  of  a  cylin- 
drical tank  having  a  conical  bottom.  In  the  center  of 
the  tank  is  a  circular  well  which  extends  nearly  to  the 
top  and  bottom,  supported  by  braces  from  the  side  of  the 
tank  and  having  a  circular  apron  at  the  top  which 
slopes  gradually  toward  the  circumference  and  per- 
mits the  ore-pulp  solution,  in  flowing  over  it,  to  be 
spread  out  into  a  thin  sheet  and  to  absorb  an  abun- 
dance of  free  oxygen.  In  this  well  is  a  hollow  shaft 
carrying  a  driving-pulley  near  the  top  and  a  number 
of  screw  propellers  or  pulp-solution  lifting- wings.  The 
discharge-valve  is  connected  to  a  screw  for  opening 
and  closing.  Outside  the  well  and  between  the  apron 
and  the  bottom  of  the  tank,  the  anode  and  cathode 
frames  or  the  electrolytic  filtering-envelope  are  sup- 
ported from  the  side  of  the  tank  and  hold  the  anodes 


SHORT   DESCRIPTIONS   OF   SOME   PROCESSES.  65 


n 


FiQ.  16. — The  Hendryx  Agitator. 


66  THE    CYANIDE    PROCESS. 

and  cathodes  which  are  supplied  with  electrical  cur- 
rent. A  coil  of  pipe  serves  for  raising  the  temperature 
of  the  charge  by  means  of  steam  or  hot  water  passing 
through  it.  The  revolutions  of  the  propellers  in  the 
well  produce  a  strong  upward  current,  thus  resulting  in 
a  rapid  and  uniform  circulation  of  the  pulp  upward  to 
the  aerating  apron,  where  it  spreads  out  into  a  thin  sheet, 
losing  its  velocity  and  gently  falling  from  the  edge  of  the 
apron  into  the  great  mass  of  ore-pulp  solution,  where  its 
velocity  is  again  reduced,  and  then  gently  dropping  down 
through  the  electrically  charged  plates  or  envelopes. 

Cannot  scour  Plates. — As  the  violence  or  force  ex- 
erted by  this  method  of  agitation  is  within  the  tube 
or  well,  and  as  the  plates  are  outside  the  well,  no 
scouring  of  the  plates  is  possible,  thereby  removing  all 
danger  of  scouring  the  deposited  metals  from  off  the 
plates,  which  is  so  common  in  all  of  the  old  arm  or 
paddle  stirring  devices. 

Agitator  cannot  be  clogged.  —  The  charge  in  this 
agitator  is  homogeneous  and  cannot  be  clogged.  A 
charge  of  76  tons  of  pulp  (30  tons  ore,  dry  weight)  in  a 
16-foot  agitator  was  settled  48  hours  on  account  of  the 
breaking  of  a  countershaft.  Upon  starting  up,  the 
pump  was  throwing  its  full  capacity  in  three  minutes, 
and  the  charge  was  in  perfect  agitation  in  ten  minutes. 

Power  required. — The  power  required  to  operate  a 
machine  of  80  to  100  tons  of  ore  pulp,  containing  one 
or  two  tons  of  solution  to  one  of  ore,  is  about  eight 
horse-power,  and  the  whole  contents  of  the  tank  are 
brought  up  and  over  the  aerating  or  distributing  plate 
once  in  five  or  ten  minutes,  at  the  pleasure  of  the  opera- 
tor, by  an  increased  or  decreased  speed  of  the  pump. 


SHORT    DESCRIPTIONS    OF    SOME    PROCESSES. 


67 


Sample  Specifications  and  Prices  of  Cyanide  Plants  for 
48  Hours'  Contact. 

SPECIFICATIONS. 

2  Solution-tanks. 

4  Leaching-tanks,  including  false  bottom,  style  A  or 
B,  Duck  Filters  and  Bottom  Discharge-doors. 

2  Gold-solution  Tanks. 

3  Zinc  Precipitation-boxes  (2  for  strong  solution  and 

1  for  weak  solution). 
2  Sump-tanks. 
1  Solution-pump. 
Acid-proof  Paint  in  sufficient  quantity  to  coat  all  tanks 

on  the  inside. 
Tank-connections . 
Cyanide  Stop-cocks. 
And  all  necessary  Pipe  and  Pipe  Fittings. 

Plants  up  to  and  including  25-ton  capacity  are  fur- 
nished with  100  pounds  of  Zinc  Shavings,  and  larger 
plants  with  a  Zinc  Lathe. 

(These  specifications  do  not  include  crushing  machinery,  furnaces, 
etc.) 

Price. 


Daily  Capacity  at  25 
Cubic  Feet  per  Ton. 

Approximate  Weight. 

Cost. 

10    tons 

16,780  Ibs. 

$1,000  00 

15 

18,760 

1,140  00 

20 

22,290 

1,335  00 

25 

26,430 

1,460  00 

40 

43,655 

2,155  00 

50 

50,570 

2,535  00 

60 

57,150 

2,720  00 

75 

63,260 

3,040  00 

100 

.    77,485 

3,800  00 

125 

101,320 

4,300  00 

150 

113,000 

4,940  00 

200 

134,150 

6,080  00 

68 


THE   CYANIDE   PROCESS. 


"iito^ 


FIG.  17. — Leaching- tanks 


FIG.  18.— Bottom  Discharge-doors.  Size  of  opening  10X10  in., 
or  16  X 16  in.  These  sluice-doors  consist  of  heavy  cast-iron  frames 
with  iron  doors  attached  by  bolt  hinges.  They  are  kept  water- 
tight by  means  of  rubber  gaskets  placed  around  the  edge  oi  the 
door  proper.  Bottom  discharge-plugs  are  used  where  it  i 
desirable  to  open  doors  from  below  a  tank.  These  plugs  are 
removed  from  inside  by  means  of  a  handle  extending  to  top  of  tank. 


SHORT   DESCRIPTIONS  OF    SOME    PROCESSES.          69 


Size. 

8X13   in. 
8X  8   " 


Weight. 
115  Ibs. 
,  90  " 


FIG.  19. — Side  Discharge-doors. 


70  THE   CYANIDE   PROCESS. 


FIG.  20. — Bottom  Discharge-gate. 


SHORT   DESCRIPTIONS    OF    SOME    PROCESSES. 


71 


FILTER  BOTTOM 
STYLE  A. 


FIG.  21. — False  Bottom  for  Leaching-tanks.  This  bottom  con- 
sists of  a  grating  built  of  Oregon-pine  strips  laid  about  1J  inches 
apart,  and  for  the  protection  of  the  filter  a  thin  band  is  placed 
around  the  outer  edge  of  these  strips.  Each  strip  is  crozed  to 
allow  of  free  flow  of  solution. 


72 


THE    CYANIDE   PROCESS. 


FIG.  22.— False  Bottom  for  Leaching-tank.  The  bottom  slats 
of  this  filter  bottom  are  similar  to  style  "A,"  but  placed  farther 
apart  on  which  a  grating  is  placed,  consisting  of  1-inch  Oregon- 
pine  strips,  laid  1  inch  apart,  with  a  suitable  strip  around  the  outer 
edge  of  slats  to  prevent  filter-cloth  from  being  cut. 


SHORT   DESCRIPTIONS    OF    SOME   PROCESSES.         73 


FIG.  23. —  This  filter  is  constructed  of  3  X  4-inch  segments, 
forming  a  complete  circle;  within  this  circle  are  placed'  the  sill- 
pieces  which  support  a  1-inch  Oregon-pine  floor  provided  with 
holes  bored  at  equal  distances. 


74 


THE    CYANIDE    PROCESS. 


Sand  Filter 


FIG.  24. — Sand  Filters.  In  some  localities  this  filter  is  very 
much  in  use.  It  consists  of  triangular  slats  resting  on  regular  sill- 
pieces.  The  spaces  between  the  slats  are  filled  with  gravel  and 
sand,  level  with  the  upper  edge,  and  no  filter-cloth  is  used  in  con- 
nection with  them. 


SHORT    DESCRIPTIONS    OF    SOME    PROCESSES. 


75 


FIG.  25. — False  Bottom,  Style  D,  sloping  5°  to  center. 

This  Filter  Bottom  consists  of  1-inch  Oregon  pine,  perforated 
with  ^-inch  holes,  1  inch  center  to  center. 

The  bottom  rests  upon  circles  3  ft.  apart.  The  circles  are  built 
up  to  different  heights,  with  openings  crozed  in  lower  part  for  free 
flow  of  solution. 

Tailings  Discharge  is  placed  in  center  of  tank,  but  tanks  above 
36  ft.  diameter  have  special  arrangement  for  four  bottom  doors. 


76 


THE    CYANIDE    PROCESS. 


FIG.  26. — Fairfax  Exploration  Co.'s  Cyanide  Plant. 


SHORT   DESCRIPTIONS   OF    SOME   PROCESSES.         77 


FIG.  27.— Cyanide  Works,  "Myall  United"  Gold-mine, 
McPhail,  N.  S.  W. 


SHORT    DESCRIPTIONS   OF   SOME   PROCESSES. 


79 


FIG.  29.— Clean-up  Room  at  the  Cyanide  Plant  of  Liberty  Bell 
Mine,  showing  Iron  Vacuum-tanks,  Zinc  Precipitating-boxee,  Vac- 
uum-pumps, Solution-pumps,  Acid-tanks. 


APPENDIX. 


Volumetric  Analysis. 

By  volumetric  analysis  the  quantity  of  a  substance 
in  a  solution  is  determined  by  another  solution  of  known 
strength,  with  which  the  solution  to  be  determined 
reacts.  When  the  reaction  is  complete,  a  precipitate 
forms,  or  ceases  to  form;  a  color  appears,  or  dis- 
appears; a  change  of  color  occurs,  or  a  change  of  color 
is  produced  in  an  indicator  put  into  the  solution  for  this 
purpose. 

End  Reaction. — The  point  in  the  operation  where  the 
reaction  is  complete,  as  indicated  by  change  of  color, 
etc.,  is  called  the  end  reaction. 

Titration  is  the  operation  of  running  a  standard  solu- 
tion into  the  solution  to  be  determined,  and  observing 
the  end  reaction:  the  operation  of  volumetric  analysis, 

Normal  Factor. — The  amount  in  grams  of  the  reagent 
in  \  cubic  centimeter  of  a  normal  solution  is  called 
the  normal  factor. 

80 


STANDARD    SOLUTIONS.  81 


Indicators. 

Litmus. — Grind  litmus  in  a  porcelain  mortar  with  a 
little  alcohol.  Transfer  to  a  flask  or  beaker,  and  pour 
some  boiling  alcohol  on  the  litmus.  After  standing 
for  some  time,  pour  off  the  alcoholic  solution,  which  is 
of  no  value.  Pour  distilled  water  on-  the  litmus,  let 
stand  for  some  time,  and  then  filter  the  solution.  Add 
dilute  hydrochloric  acid,  drop  by  drop,  to  the  blue 
solution  until  it  turns  violet  (not  red).  Keep  the 
solution  in  a  loosely  covered  vessel.  Alkalies  turn  the 
solution  blue,  and  acids  red.  Free  carbonic  acid,  C02, 
interferes  with  the  production  of  the  blue  color :  it  must 
be  boiled  out  of  the  solution.  It  cannot  be  used  by 
gaslight. 

Methyl  Orange.  —  Dissolve  1  gram  in  1000  cubic 
centimeters  of  distilled  water.  It  is  colorless,  or  faint 
yellow  with  excess  of  alkalies,  and  red,  or  pink,  with 
acids.  It  is  not  affected  by  carbonic  acid  or  sulphuretted 
hydrogen.  It  cannot  be  used  in  organic  acids  or  hot 
solutions. 

Phenacetolin. — Dissolve  in  alcohol,  in  proportion  of 
2  grams  per  1000  cubic  centimeters  of  alcohol.  It  is 
used  in  titrating  potassium  hydrate,  sodium  hydrate, 
or  calcium  oxide  in  the  presence  of  their  respective 
carbonates.  Alkalies  turn  it  pink,  and  acids  yellow. 

Starch  Solutions. — Mix  1  gram  starch  with  a  little 
cold  water,  then  pour  100  cubic  centimeters  boiling 
water  on  the  starch.  Mix  and  filter.  The  solution 
should  be  cold  when  used.  It  must  be  made  fre- 
quently, as  it  will  not  keep  for  a  long  time.  If  a  little 


82  APPENDIX. 

salicylic  acid  or  pure  common  salt  is  added,  the  solution 
will  keep  for  a  long  time.  It  is  used  in  titrating  with 
iodine.  Iodine  colors  starch  blue. 

Phenolphthalein. — Dissolve  1  gram  in  a  liter  of  50% 
alcohol.  It  is  used  in  titrating  organic  acids,  and 
fixed  caustic  alkalies  in  presence  of  carbonates.  It 
gives  no  color  with  bicarbonates,  and  cannot  be  used 
for  the  titration  of  free  ammonia  and  its  compounds, 
or  for  the  fixed  alkalies,  \vhen  salts  of  ammonia  are 
present.  It  is  purple  in  alkaline  solutions,  and  color- 
less in  acids. 


Standard  Solutions. 

Standard  Solutions. — When  a  solution  of  definite 
strength  of  a  chemical  is  made,  by  means  of  which  the 
strength  of  other  solutions  is  determined,  it  is  a  standard 
solution.  The  strength  of  which  to  make  a  standard 
solution  depends  on  the  peculiar  reaction  such  a  solu- 
tion has  with  the  solution  to  be  tested. 

Write  the  equation  for  the  reaction  between  the 
standard  solution  and  the  solution  to  be  titrated, 
from  which  the  value  of  the  standard  solution  to  the 
solution  to  be  determined  will  be  seen. 

Normal  Solutions  contain  the  hydrogen  equivalent 
of  the  reacting  element  in  grams  in  1  liter  (1000  cubic 
centimeters,  at  16°  C.  or  60°  F.) .  A  normal  solution 
is  indicated  by  the  letter  N.  Solutions  of  less  strength 
are  indicated  as  N/10  (1/10  normal,  or  decinormal), 
etc.  If  a  substance  is  univalent  (example,  HC1),  the 
full  molecular  weight  is  taken.  If  bivalent  (example, 


STANDARD    SOLUTIONS.  83 

H2S04),  half  the  molecular  weight  is  taken,  etc.  This 
rule  does  not  hold  good  in  all  cases.  (Read  paragraph 
above  beginning,  Write  the  equation  for  the  reaction.  .  .) 

All  standard  solutions  should  be  made  with  the 
greatest  care  and  accuracy,  and  should  be  kept  in 
well-stoppered  bottles.  Before  using  a  solution,  the 
bottle  containing  the  same  should  be  well  shaken,  to 
take  up  the  liquid  that  may  have  evaporated  and  con- 
densed on  the  sides  of  the  bottle,  and  to  mix  the  solu- 
tion thoroughly.  Burettes  and  all  other  measuring- 
vessels  must  be  clean  and  dry  before  a  standard  solution 
is  measured  by  them. 

Vessels  in  which  weighed  or  determined  samples  for 
standard  solutions  are  dissolved  must  be  thoroughly 
rinsed  into  the  measuring-cylinder  before  the  solution 
is  diluted  to  the  determined  volume. 

Bottles  with  glass  stoppers  and  burettes  with  glass 
stop-cocks  should  not  be  used  for  caustic-alkali  solutions, 
as  they  are  liable  to  stick  fast. 

To  make  a  Decinormal  Potassium  Hydrate,  KOH, 
Solution. — Potassium  hydrate  cannot  be  accurately 
weighed.  The  solution  must  be  standardized  against 
an  acid  which  can  be  accurately  weighed. 

Weigh  out  exactly  6.300  grams  perfectly  pure  crystals 
of  oxalic  acid  (H*CaO4.2B20«126;  126^2  =  63; 
63^10  =  6.300),  dissolve  in  distilled  water,  and  dilute 
to  exactly  1  liter  (1000  cubic  centimeters*).  This 
is  a  decinormal  oxalic  acid  solution.  Each  cubic  centi- 
meter contains  0.0063  gram  of  the  acid. 

*  Cubic  centimeters  is  usually  abbreviated  to  c.c. 


84  APPENDIX. 

Weigh  out,  approximately,  5.600  grams  pure  potas- 
sium hydrate  (KOH  =  56;  56-^-10  =  5.600),  dissolve  in 
distilled  water,  and  dilute  to  about  800  cubic  centi- 
meters. 

Take  10  cubic  centimeters  of  the  potassium  hydrate 
solution,  to  which  add  several  drops  of  litmus  solution 
(or  methyl  orange),  and  titrate  from  a  burette  by  the 
decinormal  oxalic  acid  solution,  until  the  litmus  (or 
the  methyl  orange,  if  used)  turns  red.  Note  the  number 
of  cubic  centimeters  of  oxalic  acid  consumed.  Make  a 
duplicate  titration.  Do  the  same  with  20  cubic  centi- 
meters of  the  potassium  hydrate  solution.  If  the  results 
agree  closely,  take  the  average. 

Example. — Suppose  it  took  12  cubic  centimeters  of 
the  oxalic  acid  solution  to  neutralize  10  cubic  centi- 
meters of  the  potassium  hydrate  solution.  The  potas- 
sium hydrate  solution  must  be  diluted  until  1  cubic 
centimeter  of  the  oxalic  acid  solution  will  exactly 
neutralize  1  cubic  centimeter  of  the  potassium  hydrate 
solution. 

Suppose  there  are  740  cubic  centimeters  of  the 
potassium  hydrate  solution  remaining  after  the  above 
trials : 

10:12::740:z.    z  =  888. 

Add  distilled  water  to  the  740  cubic  centimeters  of 
potassium  hydrate  solution,  until  the  whole  volume 
reaches  888  cubic  centimeters;  or  add  148  cubic  centi- 
meters water  to  the  740  cubic  centimeters  potassium 
hydrate  solution  (888-740  =  148). 


STANDARD    SOLUTIONS.  85 

Now  titrate  again.  One  cubic  centimeter  of  the  acid 
should  exactly  neutralize  1  cubic  centimeter  of  the 
potassium  hydrate  solution.  Each  cubic  centimeter 
contains  0.0056  gram  potassium  hydrate. 

To  make  a  Decinormal  Sulphuric  Acid,  H^SCU,  Solu- 
tion. —  Take  2.8  cubic  centimeters  strong  sulphuric 
acid  (1.84  sp.  gr.),  and  pour  it  into  about  800  cubic 
centimeters  distilled  water  (pour  the  acid  into  the 
water,  not  the  water  into  the  acid) .  After  the  mixture 
is  cool,  take  10  cubic  centimeters  of  the  acid  and  titrate 
from  a  burette  with  the  decinormal  potassium  hydrate 
solution  (use  litmus  or  methyl  orange  as  an  indicator). 
Note  the  number  of  cubic  centimeters  of  potassium 
hydrate  consumed  to  neutralize  the  acid.  Make  a 
duplicate  titration.  'Do  the  same  with  20  cubic  centi- 
meters. If  the  results  agree  closely,  take  the  average. 

Example—  Suppose  it  took  12  cubic  centimeters  of 
the  decinormal  potassium  hydrate  solution  to  neu- 
tralize 10  cubic  centimeters  of  the  sulphuric-acid 
solution,  and  suppose  there  are  768  cubic  centimeters 
of  the  sulphuric  acid  solution  remaining,  after  the  above 
trials: 

10:12:  :768:z.    a =921.6. 

Add  distilled  water  to  the  768  cubic  centimeters 
sulphuric  acid  until  the  whole  volume  reaches  921.6 
cubic  centimeters,  or  add  153.6  cubic  centimeters 
water  to  the  768  cubic  centimeters  sulphuric  acid 
(921.6-768  =  153.6).  After  the  mixture  is  cool,  titrate 
again.  One  cubic  centimeter  decinormal  potassium 


86  APPENDIX. 

hydrate  solution  should  exactly  neutralize  1  cubic  cen- 
timeter of  the  sulphuric  acid  solution.  Each  cubic 
centimeter  contains  0.0049  gram  sulphuric  acid. 

To  make  a  Decinormal  Nitric  Acid,  HNOs,  Solution.— 
Take  pure  nitric  acid  and  standardize  it  against  deci- 
normal  potassium  hydrate  solution,  in  the  same  way 
as  directed  for  sulphuric  acid.  In  1  cubic  centimeter 
decinormal  nitric  acid  solution  there  is  0.0063  gram  of 
the  acid. 

To  make  a  Decinormal  Iodine  Solution.  —  Procure 
three  watch-glasses  (accurately  fitting  on  one  another) 
of  convenient  size.  Weigh  two  glasses  accurately. 
Take  about  12  grams  iodine,  and  mix  it  with  about 
one-fourth  its  weight  potassium  iodide  on  the  third 
glass.  Cover  this  glass  with  one  of  the  weighed  glasses, 
which  should  not  touch  the  mixture.  Apply  heat  to 
the  glass  containing  the  mixture.  After  the  iodine 
has  sublimed  on  the  upper  glass,  remove  it  and  cover  it 
with  the  other  weighed  glass,  cool,  and  weigh. 

Example: 

Grams. 

Weight  of  glasses  and  iodine 32 . 000 

Weight  of  glasses  only 20.000 


Iodine 12.000 

A  decinormal  iodine  solution  contains  12.685  grams 
iodine  per  1000  cubic  centimeters. 

12.685:12:  :1000:z.    x  =  945.99. 

After  weighing   the   glasses   containing   the   iodine, 
place  them  immediately  in  a  beaker  containing  a  solu- 


STANDARD    SOLUTIONS.  87 

tion  of  nearly  twice  as  much  potassium  iodide  as  there 
is  iodine  by  weight  (the  potassium  iodide  must  give  no 
blue  color  to  starch,  when  dilute  sulphuric  acid  is 
added  to  a  solution  of  the  potassium  iodide  used  for 
this  purpose). 

Now  transfer  the  solution  to  a  graduated  cylinder, 
and  fill  it  up  to  the  required  volume,  945.99  cubic  centi- 
meters. Each  cubic  centimeter  contains  0.012685 
gram  iodine. 

Second  Method. — Put  some  pure  iodine  in  a  weighed, 
glass-stoppered,  weighing-bottle,  and  weigh  the  bottle 
and  iodine  (the  bottle  must  be  kept  tightly  stoppered, 
as  iodine  is  very  volatile). 

Make  a  solution  of  nearly  twice  as  much  potassium 
iodide  by  weight  as  iodine  taken,  as  in  the  first  method. 
With  this  solution  wash  the  iodine  out  of  the  weighing- 
bottle  into  a  graduated  cylinder.  Be  careful  that  all 
the  iodine  is  transferred  to  the  graduated  cylinder. 

Example. — Suppose  the  iodine  (less  the  weight  of 
the  bottle)  weighed  6.000  grams. 

12.685:6:  :1000:z.    z  =  472.99. 

Add  distilled  water  to  the  cylinder  until  the  whole 
volume  reaches  472.99  cubic  centimeters.  This  is  a 
decinormal  iodine  solution,  the  same  as  under  the  first 
method. 

Third  Method. — Powder  pure  crystals  of  -sodium 
thiosulphate,  dry  by  pressing  between  folds  of  blotting- 
paper,  and  weigh  out  exactly  24.8  grams  (Na2S203.5H20 
=248.  248-*- 10  =  24.8).  Dissolve  in  distilled  water 


88  APPENDIX. 

and  dilute  to  exactly  1000  cubic  centimeters.  This 
is  a  decinormal  solution  of  sodium  thiosulphate.  Each 
cubic  centimeter  contains  0.0248  gram  sodium  thio- 
sulphate. As  only  half  the  sodium  reacts  with  iodine^ 
the  whole  molecular  weight  of  the  sodium  thiosulphate 
will  be  contained  in  a  liter  of  a  normal  solution: 

2Na2S203  +  12  =  2NaI  +  Na2S406 

Dissolve  iodine  in  distilled  water  containing  potassium 
iodide,  as  directed  in  the  first  method.  Have  the  iodine 
solution  stronger  in  iodine  than  decinormal  (by  not 
diluting  to  that  point).  Draw  10  cubic  centimeters  of 
the  sodium  thiosulphate  solution  from  a  burette,  add 
a  little  starch  solution,  and  run  in,  from  a  burette,  the 
iodine  solution.  As  soon  as  the  iodine  is  in  excess,  it 
blues  the  starch  solution.  Make  a  duplicate,  etc.,  as 
directed  in  other  examples. 

Suppose  it  took  8  cubic  centimeters  of  the  iodine 
solution  to  neutralize  10  cubic  centimeters  of  the 
sodium  thiosulphate  solution,  and  there  are  500  cubic 
centimeters  of  the  iodine  solution  remaining: 


8:10::500:z.     z  = 


Add  distilled  water  to  the  iodine  solution  until  the 
whole  volume  reaches  625  cubic  centimeters,  or  add 
125  cubic  centimeters  water  to  the  500  cubic  centi- 
meters iodine  solution  (625-500  =  125).  This  is  a 
decinormal  solution  of  iodine,  the  same  as  under  the 
first  and  the  second  method. 


STANDAKD    SOLUTIONS.         .  89 

Iodine  solutions  should  be  occasionally  tested,  as  they 
change  after  standing  for  some  time.  In  a  well- 
stoppered  bottle  wrapped  in  brown  paper  to  exclude  the 
light,  the  solution  remains  unchanged  for  a  long  time. 

To  determine  the  Strength  of  a  Potassium  Cyanide 
Solution  by  a  Decinormal  Iodine  Solution. — In  titrat- 
ing potassium  cyanide  with  iodine,  the  reaction  is: 

21   +  KCN  =  KI+ICN. 

253.70  65 

253.70:65: : 0.012685: x.     z  =  0.00325. 

Each  cubic  centimeter  of  a  decinormal  iodine  solu- 
tion corresponds  to  0.00325  gram  potassium  cyanide. 
Use  starch  solution  as  an  indicator.  By  multiplying 
the  number  of  cubic  centimeters  of  a  decinormal  iodine 
solution  consumed  before  the  blue  color  in  the  solution 
appears,  by  0.00325,  the  weight  of  the  potassium 
cyanide  is  found  in  the  solution  tested:  from  which 
the  percentage  strength  can  be  calculated. 


ATOMIC  WEIGHTS. 


Aluminum  ..............................  Al  27.1 

Antimony  ..............................  Sb  120.4 

Arsenic  ................................  As  75.0 

Barium  ................................  Ba  137.40 

Bismuth  ...............................  Bi  208.1 

Boron  ..................................  B  11.0 

Bromine  ...............................  Br  79.95 

Cadmium  ...............................  Cd  112.4 

Carbon  ................................  C  12.0 

Calcium  ................................  Ca  40.1 

Chlorine  ...........  .'  ....................  Cl  35.45 

Chromium  ...........  ...................  Cr  52.1 

Cobalt  .................................  Co  59.0 

Copper  ................................  Cu  63.60 

Fluorine  .......  .........................  Fl  19.05 

Gold  ...................................  Au  197.2 

Hydrogen  ..............................  H  1.008 

Iodine  .................................  I  126.85 

Iron  ...................................  Fe  55.9 

Lead  ...................................  Pb  206.92 

Magnesium  .............................  Mg  24.3 

Manganese  .............................  Mn  55.0 

Mercury  ................................   Hg  200.0 

Molybdenum  ............................  Mo  96.0 

Nickel  .................................  Ni  58.70 

Nitrogen  ...............................  N  14.04 

Oxygen  ................................  O  16.0 

Phosphorus.  .  .  .  .........................  P  31.0 

Platinum  ...............................  Pt  194.9 

Potassium  ..............................  K  39.11 

Selenium  ...............................   Se  79.2 

Silicon  .................................  Si  28.4 

Silver  ..................................  Ag  107.92 

Sodium  ................................  Na  23.05 

Strontium  ..............................  Sr  87.60 

Sulphur.  .  ..............................  S  32.07 

Tellurium  ..............................  Te  127.7 

Tin  ....................................   Sn  119.0 

Titanium  ...............................  Ti  48.15 

Zinc  ...................................  Zn  65.4 

90 


INDEX. 


A 

PAGE 

Acidity 12 

Agitation  Method 8 

Amalgamation  Tests 42 

Applicability  of  Cyanide  Process  to  an  Ore 35 

Assaying  Cyanide  Solutions 27 

Atomic  Weights 90 

B 

Base  Metals 12 

Begeer  Process 57 

Betty  Process 54 

Bottom,  false 71 

C 

Calcining 43 

Calculation,  Methods  to  save 23 

Chemical  Means  of  Supplying  Oxygen 18 

Chemistry  of  the  Cyanide  Process 18 

Chloridizing  Roasting 44 

Circulating  Method 10 

Clean-up 46 

Complex  Solutions,  Titration  of 33 

Consumption  of  Cyanide 38 

Crushing 43 

91 


92  INDEX. 


PAGE 


Cyanide  Process 8 

Begeer 57 

Betty ; 54 

Bromo-Cyanogen 59 

Decantation 58 

General  Description 3 

Godbe 57 

Hendryx 61 

Holderman 60 

McArthur-Forest 52 

Moore 61 

Pneumatic 54 

Siemen-Halske 52 

Zinc-dust  Precipitation 58 

D 

Decantation  Process • 58 

Decomposition  of  Potassium  Cyanide 19 

Definite  Volume  of  Solution 25 

Door,  bottom 68 

side 69 

Double-treatment  Method 10 

E 

Extraction  Tests 36 

G 

Godbe  Process 57 

H 

Hendryx  Cyanide  Process 61 

Holderman  Cyanide  Process 60 


INDEX.  93 


PAGE 

Interfering  Substances,  Acidity 12 

Aluminum 17 

Antimony    „ 17 

Arsenic 17 

Base  Metals 12 

Cobalt 17 

Copper 15 

Iron 14 

Iron  Sulphides 17 

Magnesium 17 

Manganes 17 

Organic  Matter 17 

Introductory 1 

Iodine,  Decinormal  Solution 86 

M 

McArthur-Forest  Process 52 

Mechanical  Means  to  supply  Oxygen 18 

Methods  of  operating  the  Cyanide  Process 8 

Methods  to  save  Calculations 23 

Moore  Cyanide  Process 61 

N 

Nitric  acid 86 

O 

Operating,  Methods  of 8 

Oxygen,  Means  of  Supplying 18 

P 

Percolation  Method 8 

Pneumatic  Process 54 


94  INDEX. 

PAGE 

Potassium  Cyanide,  Decomposition  of 19 

Potassium  Hydrate,  Decinormal  Solution 83 

Precipitating  Gold  from  Cyanide  Solution,  Methods  of. ...  11 

Precipitation  Tests 41 

R 

Reactions  in  the  Zinc  Boxes 20 

Roasting 44 

S 

Solutions,  Determination  of  Strength. 21 

Strength  of 20,  43 

Siemens-Halske  Process 52 

Silver  Ores 45 

Specifications  and  Prices  of  Cyanide  Plants 67 

Sulphuric  Acid,  Decinormal  Solution 85 

T 

Testing  Cyanide  Solutions  containing  Zinc 30 

Tests,  Extraction ' 36 

Titrating  Complex  Solutions 33 

U 

Useful  Information 51 


Vats 63 

Volumetric  Analysis 80 

Decinormal  Iodine  Solution 86 

Nitric  Acid  Solution 86 

Potassium  Hydrate  Solution 83 

Sulphuric  Acid  Solution 85 


.   INDEX. 


95 


W 

PAGE 

Weak  Solutions,  to  bring  to  Strength  ...................     24 


Zinc  Boxes,  Reactions  in  ..............................     20 

Zinc-dust  Precipitation.  „  .............................     58 


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*  Bruff's  Text-book  Ordnance  and  Gunnery 8vo,    6  oo 

Chase's  Screw  Propellers  and  Marine  Propulsion 8vo,    3  oo 

Cloke's  Gunner's  Examiner.     (In  press.) 

Craig's  Azimuth 4to,  3  50 

Crehore  and  Squier's  Polarizing  Photo-chronograph 8vo,  3  oc 

Cronkhite's  Gunnery  for  Non-commissioned  Officers 241110,  morocco,  2  oa 

*  Davis's  Elements  of  Law 8vo,  2  se 

*  Treatise  on  the  Military  Law  of  United  States 8vo,    7  ec 

Sheep,  7  50 

De  Brack's  Cavalry  Outposts  Duties.     (Carr.) 24mo,  morocco,  2  oo 

Dietz's  Soldier's  First  Aid  Handbook i6mo,  morocco,  i  25 

*  Dredge's  Modern  French  Artillery. 4to,  half  morocco,  15  oe 

Durand's  Resistance  and  Propulsion  of  Ships 8vo,  5  oc 

*  Dyer's  Handbook  of  Light  Artillery i2mo,  3  oc 

Eissler's  Modern  High  Explosives 8vo,  4  oc 

*  Fiebeger's  Text-book  on  Field  Fortification Small  8vo,  2  oc 

Hamilton's  The  Gunner's  Catechism i8mo,  i  oc 

*  Hoff' s  Elementary  Naval  Tactics 8vo,  i  sc 

Ingalls's  Handbook  of  Problems  in  Direct  Fire 8vo,  4  oc 

*  Ballistic  Tables 8vo,    i  sc 

*  Lyons's  Treatise  on  Electromagnetic  Phenomena.  Vols.  I.  and  II. .  8vo,  each,  6  oe 

*  Mahan's  Permanent  Fortifications.    (Mercur.) 8vo,  half  morocco,  7  sc 

Manual  for  Courts-martial i6mo,  morocco,  i  sc 

*  Mercur's  Attack  of  Fortified  Places i2mo,  2  oc 

*  Elements  of  the  Art  of  War 8vo,  4  o( 

Metcalf's  Cost  of  Manufactures — And  the  Administration  of  Workshops.  .8vo,  5  o< 

*  Ordnance  and  Gunnery.     2  vols i2mo,  5  o< 

Murray's  Infantry  Drill  Regulations i8mo,  paper,  i< 

Nixon's  Adjutants'  Manual 24010,  i  o< 

Peabody's  Naval  Architecture 8vo,  7  5< 


*  Phelps's  Practical  Marine  Surveying 8vo,  2  50 

Powell's  Army  Officer's  Examiner i2mo,  4  oo 

Sharpe's  Art  of  Subsisting  Armies  in  War iSmo^  morocco,  i  50 

*  Walke's  Lectures  on  Explosives 8vo,  4  oo 

*  Wheeler's  Siege  Operations  and  Military  Mining 8vo,  2  oo 

Winthrop's  Abridgment  of  Military  Law .- i2mo,  2  50 

Woodhull's  Notes  on  Military  Hygiene i6mo,  i  50 

Young's  Simple  Elements  of  Navigation i6mo,  morocco,  i  oo 

Second  Edition,  Enlarged  and  Revised i6mo,  morocco,  2  oo 

ASSAYING. 

Fletcher's  Practical  Instructions  in  Quantitative  Assaying  with  the  Blowpipe. 

i2mo,  morocco,  i  50 

Furman's  Manual  of  Practical  Assaying 8vo,  3  oo 

Lodge's  Notes  on  Assaying  and  Metallurgical  Laboratory  Experiments.  .  .  .8vo,  3  oo 

Miller's  Manual  of  Assaying I2mo,  i  oo 

O'Driscoll's  Notes  on  the  Treatment  of  Gold  Ores 8vo,  2  oo 

Ricketts  and  Miller's  Notes  on  Assaying 8vo,  3  oo 

Ulke's  Modern  Electrolytic  Copper  Refining 8vo,  3  oo 

Wilson's  Cyanide  Processes i2mo,  i  50 

Chlorination  Process * i2mo,  i  50 

ASTRONOMY. 

Comstock's  Field  Astronomy  for  Engineers 8vo,  2  50 

Craig's  Azimuth 4to,  3  50 

Doolittle's  Treatise  on  Practical  Astronomy 8vo,  4  oo 

Gore's  Elements  of  Geodesy 8vo,  2  50 

Hayford's  Text-book  of  Geodetic  Astronomy 8vo,  3 .  oo 

Merriman's  Elements  of  Precise  Surveying  and  Geodesy 8vo,  2  50 

*  Michie  and  Harlow's  Practical  Astronomy 8vo,  3  oo 

*  White's  Elements  of  Theoretical  and  Descriptive  Astronomy I2mo,  2  oo 

BOTANY. 

Davenport's  Statistical  Methods,  with  Special  Reference  to  Biological  Variation. 

i6mo,  morocco,     i  25 

Thome'  and  Bennett's  Structural  and  Physiological  Botany i6mo,    2  25 

Westermaier's  Compendium  of  General  Botany.     (Schneider.) 8vo,    2  oo 

CHEMISTRY. 

Adriance's  Laboratory  Calculations  and  Specific  Gravity  Tables I2mo,  i  25 

Allen's  Tables  for  Iron  Analysis 8vo,  3  oo 

Arnold's  Compendium  of  Chemistry.     (Mandel.) Small  8vo,  3  50 

Austen's  Notes  for  Chemical  Students i2mo,  i  50 

Bernadou's  Smokeless  Powder. — Nitro-cellulose,  and  Theory  of  the  Cellulose 

Molecule I2mo,  2  50 

Bolton's  Quantitative  Analysis 8vo,  i  50 

*  Browning's  Introduction  to  the  Rarer  Elements. 8vo,  i  50 

Brush  and  Penfield's  Manual  of  Determinative  Mineralogy 8vo,  4  oo 

Classen's  Quantitative  Chemical  Analysis  by  Electrolysis.    (Boltwood.).  .8vo,  3  oo 

Cohn's  Indicators  and  Test-papers i2mo,  2  oo 

Tests  and  Reagents 8vo,  3  oo 

Crafts's  Short  Course  in  Qualitative  Chemical  Analysis.   (Schaeffer.). .  .i2mo,  i  50 
Dolezalek's  Theory  of  the  Lead  Accumulator   (Storage  Battery).        (Von 

Ende.) I2mo,  2  50 

Drechsel's  Chemical  Reactions.     (Merrill.) i2mo,  i  25 

Duhem's  Thermodynamics  and  Chemistry.     (Burgess.) .8vo,  4  oo 

Eissler's  Modern  High  Explosives 8vo,  4  oo 

Effront's  Enzymes  and  their  Applications.     (Prescott.) 8vo,  3  oo 

Efdmann's  Introduction  to  Chemical  Preparations.     (Dunlap.) I2mo,  i  25 


Fletcher's  Practical  Instructions  in  Quantitative  Assaying  with  the  Blowpipe. 

i2mo,  morocco,  i  50 

Fowler's  Sewage  Works  Analyses: i2mo,  2  oc 

Fresenius's  Manual  of  Qualitative  Chemical  Analysis.     (Wells.) 8vo,  5  oc 

Manual  of  Qualitative  Chemical  Analysis.  Part  I.  Descriptive.  (Wells.)  8vo,  3  o« 
System  of    Instruction    in    Quantitative    Chemical   Analysis.      (Cohn.) 

2  vols 8vo,  12  50 

Fuertes's  Water  and  Public  Health i2mo,  i  50 

Furman's  Manual  of  Practical  Assaying 8vo,  3  oo 

*  Getman's  Exercises  in  Physical  Chemistry I2mo,  2  oo 

Gill's  Gas  and  Fuel  Analysis  for  Engineers i2mo,  i  25 

Grotenfelt's  Principles  of  Modern  Dairy  Practice.     (Woll.) i2mo,  2  oo 

Hammarsten's  Text-book  of  Physiological  Chemistry.     (Mandel.) 8vo,  4  oo 

Helm's  Principles  of  Mathematical  Chemistry.     (Morgan.) i2mo,  i  50 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  morocco,  2  50 

Hind's  Inorganic  Chemistry 8vo,  3  oo 

*  Laboratory  Manual  for  Students 12010,  75 

Holleman's  Text-book  of  Inorganic  Chemistry.     (Cooper.) 8vo,  2  50 

Text-book  of  Organic  Chemistry.     (Walker  and  Mott.) 8vo,  2  50 

*  Laboratory  Manual  of  Organic  Chemistry.     (Walker.) i2mo,  i  oo 

Hopkins*  s  Oil-chemists'  Handbook 8vo,  3  oo 

Jackson's  Directions  for  Laboratory  Work  in  Physiological  Chemistry.  .8vo,  i  25 

Keep's  Cast  Iron 8vo,  2  50 

Ladd's  Manual  of  Quantitative  Chemical  Analysis i2mo,  i  oo 

Landauer's  Spectrum  Analysis.     (Tingle-.) 8vo,  3  oo 

*  Langworthy  and   Austen.        The   Occurrence  of  Aluminium  in  Vegetable 

Products,  Animal  Products,  and  Natural  Waters 8vo,  2  oo 

Lassar-Cohn's  Practical  Urinary  Analysis.  (Lorenz.) i2mo,  i  oo 

Application  of  Some  General  Reactions  to  Investigations  in  Organic 

Chemistry.  (Tingle.) i2mo,  i  oo 

Leach's  The  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control. 8vo,  7  50 

Lob's  Electrolysis  and  Electrosynthesis  of  Organic  Compounds.  (Lorenz. ).i2mo,  i  oo 

Lodge's  Notes  on  Assaying  and  Metallurgical  Laboratory  Experiments. ..  .8vo,  3  oo 

Lunge's  Techno-chemical  Analysis.  (Cohn.) i2mo,  i  oo 

Mandel's  Handbook  for  Bio-chemical  Laboratory i2mo,  i  50 

*  Martin's  Laboratory  Guide  to  Qualitative  Analysis  with  the  Blowpipe .  .  i2mo,  60 
Mason's  Water-supply.     (Considered  Principally  from  a  Sanitary  Standpoint.) 

3d  Edition,  Rewritten 8vo,  4  oo 

Examination  of  Water.     (Chemical  and  Bacteriological.) i2mo,  i  25 

Matthew's  The  Textile  Fibres 8vo,  3  5<> 

Meyer's  Determination  of  Radicles  in  Carbon  Compounds.     (Tingle.).  .  i2mo,  i  oo 

Miller's  Manual  of  Assaying i2mo,  i  oo 

Mixter's  Elementary  Text-book  of  Chemistry. i2mo,  i  50 

Morgan's  Outline  of  Theory  of  Solution  and  its  Results i2iiio,  i  oo 

Elements  of  Physical  .Chemistry i2mo,  2  oo 

Morse's  Calculations  used  in  Cane-sugar  Factories i6mo,  morocco,  i  50 

Mulliken's  General  Method  for  the  Identification  of  Pure  Organic  Compounds. 

Vol.  I Large  8vo,  5  oo 

O'Brine's  Laboratory  Guide  in  Chemical  Analysis 8vo,  2  oo 

O'Driscoll's  Notes  on  the  Treatment  of  Gold  Ores 8vo,  2  oo 

Ostwald's  Conversations  on  Chemistry.     Part  One.     (Ramsey.) i2mo,  150 

Ostwald's  Conversations  on  Chemistry.     Part  Two.     (Turnbull.).     (In  Press.) 

*  Penfield's  Notes  on  Determinative  Mineralogy  and  Record  of  Mineral  Tests. 

8vo,  paper,  50 

Pictet's  The  Alkaloids  and  their  Chemical  Constitution.     (Biddle.) 8vo,  5  oo 

Pinner's  Introduction  to  Organic  Chemistry.     (Austen.) i2mo,  i  50 

Poole's  Calorific  Power  of  Fuels 8vo,  3  oo 

Prescott  and  Winslow's  Elements  of  Water  Bacteriology,  with  Special  Refer- 
ence to  Sanitary  Water  Analysis i2mo,  i  25 


*  Reisig's  Guide  to  Piece-dyeing.  .  .      v 8vo,  25  oo 

Richards  and  Woodman's  Air,  Water,  and  Food  from  a  Sanitary  Standpoint  8vo,  2  oo 

Richards's  Cost  of  Living  as  Modified  by  Sanitary  Science i2mo,  i  oo 

Cost  of  Food,  a  Study  in  Dietaries I2mo,  i  oo 

*  Richards  and  Williams's  The  Dietary  Computer 8vo,  i  50 

Ricketts  and  Russell's  Skeleton  Notes  upon  inorganic  Chemistry.     (Part  I. 

Non-metallic  Elements.) 8vo,  morocco,  75 

Ricketts  and  Miller's  Notes  on  Assaying 8vo,  3  oo 

Rideal's  Sewage  and  the  Bacterial  Purification  of  Sewage 8vo,  3  50 

Disinfection  and  the  Preservation  of  Food 8vo,  4  oo 

Rigg's  Elementary  Manual  for  the  Chemical  Laboratory 8vo,  i  25 

Rostoski's  Serum  Diagnosis.  (Bolduan.) i2mo,  i  oo 

Ruddiman's  Incompatibilities  in  Prescriptions 8vo,  2  oo 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Salkowski's  Physiological  and  Pathological  Chemistry.  (Orndorff.) 8vo,  2  50 

Schimpf's  Text-book  of  Volumetric  Analysis i2mo,  2  50 

Essentials  of  Volumetric  Analysis i2mo,  i  25 

Spencer's  Handbook  for  Chemists  of  Beet-sugar  Houses i6mo,  morocco,  3  oo 

Handbook  for  Sugar  Manufacturers  and  their  Chemists.  .  i6mo,  morocco,  2  oo 

Stockbridge's  Rocks  and  Soils 8vo,  2  50 

*  Tillman's  Elementary  Lessons  in  Heat 8vo,  i  50 

*  Descriptive  General  Chemistry 8vo,  3  oo 

Treadwell's  Qualitative  Analysis.     (Hall.) 8vo,  3  oo 

Quantitative  Analysis.     (Hall.) 8vo,  4  oo 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Van  Deventer's  Physical  Chemistry  for  Beginners.     (Boltwood.) i2mo,  i  50 

*  Walke's  Lectures  on  Explosives 8vo,  4  oo 

Washington's  Manual  of  the  Chemical  Analysis  of  Rocks 8vo,  2  oo 

Wassermann's  Immune  Sera :  Haemolysins,  Cytotoxins,  and  Precipitins.    (Bol- 
duan.)   i2mo,  i  oo 

Well's  Laboratory  Guide  in  Qualitative  Chemical  Analysis 8vo,  i  50 

Short  Course  in  Inorganic  Qualitative  Chemical  Analysis  for  Engineering 

Students i2mo,  i  50 

Text-book  of  Chemical  Arithmetic.     (In  press.) 

Whipple's  Microscopy  of  Drinking-water 8vo,  3  50 

Wilson's  Cyanide  Processes i2mo,  i  50 

Chlorination  Process i2mo,  i  50 

Wulling's    Elementary    Course   in  Inorganic,  Pharmaceutical,  and  Medical 

Chemistry i2mo,  2  oo 

CIVIL  ENGINEERING. 

BRIDGES    AND    ROOFS.       HYDRAULICS.       MATERIALS   OF    ENGINEERING.' 
RAILWAY  ENGINEERING. 

Baker's  Engineers'  Surveying  Instruments i2mo,  3  oo 

Bixby's  Graphical  Computing  Table Paper  19^X24!  inches.  25 

**  Burr's  Ancient  and  Modern  Engineering  and  the  Isthmian  Canal.     (Postage, 

27  cents  additional.) 8vo,  3  50 

Comstock's  Field  Astronomy  for  Engineers 8vo,  2  50 

Davis's  Elevation  and  Stadia  Tables 8vo,  i  oo 

Elliott's  Engineering  for  Land  Drainage i2mo,  i  50 

Practical  Farm  Drainage i2mo,  i  oo 

Fiebeger's  Treatise  on  Civil  Engineering.     (In  press.) 

Folwell's  Sewerage.     (Designing  and  Maintenance.) 8vo,  3  oo 

Freitag's  Architectural  Engineering.     2d  Edition,  Rewritten 8vo,  3  50 

French  and  Ives's  Stereotomy 8vo,  2  50 

Goodhue's  Municipal  Improvements *.  I2mo,  I  75 

Goodrich's  Economic  Disposal  of  Towns'  Refuse 8vo,  3  50 

Gore's  Elements  of  Geodesy 8vo,  2  50 

Hayford's  Text-book  of  Geodetic  Astronomy §vo,  3  oo 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  morocco,  2  50 

5 


Howe's  Retaining  Walls  for  Earth izmo,  i  35 

Johnson's  (J.  B.)  Theory  and  Practice  of  Surveying Small  8vo,  4  oo 

Johnson's  (L.  J.)  Statics  by  Algebraic  and  Graphic  Methods 8vo,  2  oo 

Laplace's  Philosophical  Essay  on  Probabilities.    (Truscott  and  Emory.) .  i2mo,  2  oo 

Mahan's  Treatise  on  Civil  Engineering.     (1873.)     (Wood.) 8vo,  5  oo 

*  Descriptive  Geometry 8vo,  i  50 

Merriman's  Elements  of  Precise  Surveying  and  Geodesy 8vo,  2  50 

Elements  of  Sanitary  Engineering 8vo,  2  oo 

Merriman  and  Brooks's  Handbook  for  Surveyors i6mo,  morocco,  2  oo 

Nugent's  Plane  Surveying '. 8vo,  3  50 

Ogden's  Sewer  Design : i2mo,  2  oo 

Patton's  Treatise  on  Civil  Engineering 8vo  half  leather,  7  50 

Reed's  Topographical  Drawing  and  Sketching 4to,  5  oo 

Rideal's  Sewage  and  the  Bacterial  Purification  of  Sewage 8vo,  3  50 

Siebert  and  Biggin's  Modern  Stone-cutting  and  Masonry , 8vo,  i  50 

Smith's  Manual  of  Topographical  Drawing.     (McMillan.) 8vo,  2  50 

Sondericker's  Graphic  Statics,  with  Applications  to  Trusses,  Beams,  and  Arches. 

8vo,  2  oo 

Taylor  and  Thompson's  Treatise  on  Concrete,  Plain  and  Reinforced 8vo,  5  oo 

*  Trautwine's  Civil  Engineer's  Pocket-book i6mo,  morocco,  5  oo 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture  8vo,  5  oo 

Sheep,  5  50 

Law  of  Contracts 8vo,  3  oo 

Warren's  Stereotomy — Problems  in  Stone-cutting 8vo,  2  50 

Webb's  Problems  in  the  Use  and  Adjustment  of  Engineering  Instruments. 

i6mo,  morocco,  i   25 

*  Wheeler  s  Elementary  Course  of  Civil  Engineering 8vo,  4  oo 

Wilson's  Topographic  Surveying 8vo,  3  50 

BRIDGES  AND  ROOFS. 

Boiler's  Practical  Treatise  on  the  Construction  of  Iron  Highway  Bridges .   8vo,  2  oo 

*  Thames  River  Bridge 4to,  paper,  5  oo 

Burr's  Course  on  the  Stresses  in  Bridges  and  Roof  Trusses,  Arched  Ribs,  and 

Suspension  Bridges 8vo,  3  50 

Burr  and  Falk's  Influence  Lines  for  Bridge  and  Roof  Computations.  .  .  .8vo,  3  oo 

Du  Bois's  Mechanics  of  Engineering.     Vol.  II Small  4to,  10  oo 

Foster's  Treatise  on  Wooden  Trestle  Bridges 4to,  5  oo 

Fowler's  Ordinary  Foundations 8vo,  3  50 

Greene's  Roof  Trusses 8vo,  i  25 

Bridge  Trusses 8vo,  2  50 

Arches  in  Wood,  Iron,  and  Stone 8vo,  2  50 

Howe's  Treatise  on  Arches 8vo,  4  oo 

Design  of  Simple  Roof-trusses  in  Wood  and  Steel 8vo,  2  oo 

Johnson,  Bryan,  and  Turneaure's  Theory  and  Practice  in  the  Designing  of 

Modern  Framed  Structures Small  4to,  10  oo 

Merriman  and  Jacoby's  Text-book  on  Roofs  and  Bridges: 

Part  I.     Stresses  in  Simple  Trusses 8vo,  2  50 

Part  n.     Graphic  Statics 8vo,  2  50 

Part  III.     Bridge  Design 8vo,  2  50 

Part  IV.     Higher  Structures 8vo,  2  50 

Morison's  Memphis  Bridge .^ 4to,  10  oo 

Waddell's  De  Pontlbus,  a  Pocket-book  for  Bridge  Engineers.  .  i6mo,  morocco,  3  oo 

Specifications  for  Steel  Bridges i2mo,  i  25 

Wood's  Treatise  on  the  Theory  of  the  Construction  of  Bridges  and  Roofs .  .  8vo,  2  c  ^ 
Wright's  Designing  of  Draw-spans : 

Part  I.     Plate-girder  Draws 8vo,  2  50 

Part  H.     Riveted-truss  and  Pin-connected  Long-span  Draws 8vo,  2  50 

Two  parts  in  one  volume. 8vo,  3  So 


HYDRAULICS. 

Bazin's  Experiments  upon  the  Contraction  of  the  Liquid  Vein  Issuing  from 

an  Orifice.     (Trautwine.) 8vo,  2  oo 

Bovey's  Treatise  on  Hydraulics 8vo,  5  oo 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

Diagrams  of  Mean  Velocity  of  Water  in  Open  Channels payer,  i  50 

Coffin's  Graphical  Solution  of  Hydraulic  Problems i6mo,  morocco,  2  50 

Flather's  Dynamometers,  and  the  Measurement  of  Power 12010,  3  oo 

Polwell's  Water-supply  Engineering 8vo,  4  oo 

Frizell's  Water-power 8vo,  5  o^ 

Fuertes's  Water  and  Public  Health i2mo,  i  50 

Water-filtration  Works i2mo,  2  50 

Ganguillet  and  Kutter's  General  Formula  for  the  Uniform  Flow  of  Water  in 

Rivers  and  Other  Channels.     (Hering  and  Trautwine.) 8vo  4  oo 

Hazen's  Filtration  of  Public  Water-supply 8vo,  3  oo 

Hazlehurst's  Towers  and  Tanks  for  Water-works 8vo,  2  50 

Herschel's  115  Experiments  on  the  Carrying  Capacity  of  Large,  Riveted,  Metal 

Conduits 8vo,  2  oo 

Mason's  Water-supply.     (Considered  Principally  from  a  Sanitary  Standpoint.) 

8vo,  4  oo 

Merriman's  Treatise  on  Hydraulics 8vo,  5  oo 

*  Michie's  Elements  of  Analytical  Mechanics .  .8vo,  4  oo 

Schuyler's   Reservoirs  for  Irrigation,   Water-power,   and   Domestic   Water- 
supply Large  8vo,  5  oo 

**  Thomas  and  Watt's  Improvement  of  Rivers.     (Post.,  440.  additional. ).4to,  6  oo 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Wegmann's  Design  and  Construction  of  Dams 4to,  5  oo 

Water-supply  of  the  City  of  New  York  from  1658  to  1895 4to,  10  oo 

Wilson's  Irrigation  Engineering ,  .Small  8vo,  4  oo 

Wolff's  Windmill  as  a  Prime  Mover 8vo,  3  oo 

Wood's  Turbines 8vo,  2  50 

Elements  of  Analytical  Mechanics 8vo,  3  oo 

MATERIALS  OF  ENGINEERING. 

Baker's  Treatise  on  Masonry  Construction ,  . .  .  .8vo,  5  oo 

Roads  and  Pavements 8vo,  5  oo 

Black's  United  States  Public  Works Oblong  4to,  5  oo 

Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  50 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering 8vo,  7  50 

Byrne's  Highway  Construction 8vo,  5  oo 

Inspection  of  the  Materials  and  Workmanship  Employed  in  Construction. 

i6mo,  3  oo 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

Du  Bois's  Mechanics  of  Engineering.     Vol.  I Small  4to,  7  50 

Johnson's  Materials  of  Construction Large  8vo,  6  oo 

Fowler's  Ordinary  Foundations 8vo,  3  50 

Keep's  Cast  Iron 8vo,  2  50 

Lanza's  Applied  Mechanics 8vo,  7  50 

Marten's  Handbook  on  Testing  Materials.     (Henning.)     2  vols 8vo,  7  50 

Merrill's  Stones  for  Building  and  Decoration 8vo,  5  oo 

Merriman's  Text-book  on  the  Mechanics  of  Materials 8vo,  4  oo 

Strength  of  Materials izmo,  i  oo 

Metcalf's  Steel.     A  Manual  for  Steel-users i2mo,  2  oo 

Patton's  Practical  Treatise  on  Foundations .. 8vo,  5  09 

Richardson's  Modern  Asphalt  Pavements 8vo,  3  oo 

Richey's  Handbook  for  Superintendents  of  Construction lOmo,  mor.,  4  oo 

Rockwell's  Roads  and  Pavements  in  France I2mo,  i  35 

7 


Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Smith's  Materials  of  Machines i2mo,  i  oo 

Snow's  Principal  Species  of  Wood.  •„ 8vo,  3  50 

Spalding's  Hydraulic  Cement i2mo,  2  oo 

Text-book  on  Roads  and  Pavements • I2mo,  2  oo 

Taylor  and  Thompson's  Treatise  on  Concrete,  Plain  and  Reinforced 8vo,  5  oo 

Thurston's  Materials  of  Engineering.     3  Parts 8vo,  8  oo 

Part  I.     Non-metallic  Materials  of  Engineering  and  Metallurgy 8vo,  2  oo 

Part  II.     Iron  and  SteeL . ; 8vo,  3  50 

Part  in.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Thurston's  Text-book  of  the  Materials  of  Construction 8vo,  5  oo 

Tillson's  Street  Pavements  and  Paving  Materials 8vo,  4  oo 

WaddelPs  De  Pontibus.    CA  Pocket-book  for  Bridge  Engineers.).  .i6mo,  mor.,  3  oo 

Specifications  for  Stc  i  Bridges i2mo,  i  25 

Wood's  (De  V.)  Treatise  on  the  Resistance  of  Materials,  and  an  Appendix  on 

the  Preservation  of  Timber 8vo,  2  oo 

Wood's  (De  V.)  Elements  of  Analytical  Mechanics 8vo,  3  oo 

Wood's  (M.  P.)  Rustless  Coatings:    Corrosion  and  Electrolysis  of  Iron  and 

SteeL 8vo,  4  oo 

RAILWAY  ENGINEERING. 

Andrew's  Handbook  for  Street  Railway  Engineers 3x5  inches,  morocco,  i  25 

Berg's  Buildings  and  Structures  of  American  Railroads 4to,  5  oo 

Brook's  Handbook  of  Street  Railroad  Location i6mo,  morocco,  i  50 

Butt's  Civil  Engineer's  Field-book i6mo,  morocco,  2  50 

Crandall's  Transition  Curve i6mo,  morocco,  i  50 

Railway  and  Other  Earthwork  Tables 8vo,  i  50 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book. .  i6mo,  morocco,  5  oo 

Dredge's  History  of  the  Pennsylvania  Railroad:   (1879) Paper,  5  oo 

*  Drinker's  Tunnelling,  Explosive  Compounds,  and  Rock  Drills. 4to,  half  mor.,  25  oo 

Fisher's  Table  of  Cubic  Yards Cardboard,  25 

Godwin's  Railroad  Engineers'  Field-book  and  Explorers'  Guide.  .  .  i6mo,  mor.,  2  50 

Howard's  Transition  Curve  Field-book i6mo,  morocco,  i  50 

Hudson's  Tables  for  Calculating  the  Cubic  Contents  of  Excavations  and  Em- 
bankments  8vo,  i  oo 

Molitor  and  Beard's  Manual  for  Resident  Engineers i6mo,  i  oo 

Wagle's  Field  Manual  for  Railroad  Engineers i6mo,  morocco,  3  oo 

Philbrick's  Field  Manual  for  Engineers i6mo,  morocco,  3  oo 

Searles's  Field  Engineering i6mo,  morocco,  3  oo 

Railroad  Spiral i6mo,  morocco,  i  50 

Taylor's  Prismoidal  Formulae  and  Earthwork 8vo,  i  50 

*  Trautwine's  Method  of  Calculating  the  Cube  Contents  of  Excavations  and 

Embankments  by  the  Aid  of  Diagrams 8vo,  2  oa 

The  Field  Practice  of  Laying  Out  Circular  Curves  for  Railroads. 

I2mo,  morocco,  2  50 

Cross-section  Sheet Paper,  25 

Webb's  Railroad  Construction i6mo,  morocco,  5  oo 

Wellington's  Economic  Theory  of  the  Location  of  Railways Small  8vo,  5  oo 

DRAWING. 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  oo 

*  "                   "                   "        Abridged  Ed 8vo,  150 

Coolidge's  Manual  of  Drawing 8vo,  paper  i  oo 

Coolidge  and  Freeman's  Elements  of  General  Drafting  for  Mechanical  Engi- 
neers  \ Oblong  4to,  2  50 

Durley's  Kinematics  of  Machines 8vo,  4  oo 

Emch's  Introduction  to  Projective  Geometry  and  its  Applications 8vo.  2  50 

R 


Hill's  Text-book  on  Shades  and  Shadows,  and  Perspective 8vo,  2  oo 

Jamison's  Elements  of  Mechanical  Drawing , 8vo,  2  50 

Jones's  Machine  Design: 

Part  I.     Kinematics  of  Machinery 8vo,  i  50 

Part  II.     Form,  Strength,  and  Proportions  of  Parts 8vo,  3  oo 

MacCord's  Elements  of  Descriptive  Geometry 8vo,  3  oo 

Kinematics;  or,  Practical  Mechanism 8vo,  5  oo 

Mechanical  Drawing 4to,  4  oo 

Velocity  Diagrams 8vo,  i  50 

*  Mahan's  Descriptive  Geometry  and  Stone-cutting 8vo,  i  50 

Industrial  Drawing.     (Thompson.) 8vo,  3  50 

Moyer's  Descriptive  Geometry 8vo,  2  oo 

Reed's  Topographical  Drawing  and  Sketching 4to,  5  oo 

Reid's  Course  in  Mechanical  Drawing 8vo,  2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design. 8vo,  3  oo 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  oo 

Smith's  Manual  of  Topographical  Drawing.     (McMillan.) 8vo, 


Warren's  Elements  of  Plane  and  Solid  Free-hand  Geometrical  Drawing.  i2mo, 

Drafting  Instruments  and  Operations i2mo: 

Manual  of  Elementary  Projection  Drawing I2mo, 

Manual  of  Elementary  Problems  in  the  Linear  Perspective  of  Form  and 

Shadow i2mo, 

Plane  Problems  in  Elementary  Geometry I2mo, 


50 
oo 


25 


oo 
25 

Primary  Geometry  ................  .  .........................  I2mo,  75 

Elements  of  Descriptive  Geometry,  Shadows,  and  Perspective  .......  8vo,  3  50 

General  Problems  of  Shades  and  Shadows  ........................  8vo,  3  oo 

Elements  of  Machine  Construction  and  Drawing  ..................  8vo,  7  50 

Problems,  Theorems,  and  Examples  in  Descriptive  Geometry  .......  8vo,  2  50 

Weisbach's  Kinematics  and  Power  of  Transmission.    (Hermann  and  Klein)8vo,  5  oo 

Whelpley's  Practical  Instruction  in  the  Ait  of  Letter  Engraving  .......  i2mo,  2  oo 

Wilson's  (H.  M.)  Topographic  Surveying  .............................  8vo,  3  50 

Wilson's  (V.  T.)  Free-hand  Perspective  ..............................  8vo,  2  50 

Wilson's  (V.  T.)  Free-hand  Lettering  ...............................  8vo,  i  oo 

Woolf's  Elementary  Course  in  Descriptive  Geometry  .............  Large  8vo,  3  oo 


ELECTRICITY  AND  PHYSICS. 

Anthony  and  Brackett's  Text-book  of  Physics.     (Magie.) Small  8vo,  3  oo 

Anthony's  Lecture-notes  on  the  Theory  of  Electrical  Measurements I2mo,  i  oo 

Benjamin's  History  of  Electricity 8vo,  3  oo 

Voltaic  Cell 8vo,  3  oo 

Classen's  Quantitative  Chemical  Analysis  by  Electrolysis.     (Boltwood.).Svo,  3  oo 

Crehore  and  Squier's  Polarizing  Photo-chronograph 8vo,  3  oo 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book.  i6mo,  morocco,  5  oo 
Dolezalek's   Theory   of   the    Lead   Accumulator    (Storage    Battery).      (Von 

Ende.) i2mo,  2  50 

Duhem's  Thermodynamics  and  Chemistry.     (Burgess.) 8vo,  4  oo 

Flather's  Dynamometers,  and  the  Measurement  of  Power I2mo,  3  oo 

Gilbert's  De  Magnete.     (Mottelay.) 8vo,  a  50 

Hanchett's  Alternating  Currents  Explained I2mo,  i  oo 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  morocco,  2  50 

Holman's  Precision  of  Measurements 8vo,  2  oo 

Telescopic   Mirror-scale  Method,  Adjustments,  and  Tests. . .  .Large  8vo,  75 

Kinzbrunner's  Testing  of  Continuous-Current  Machines ' 8vo,  2  oo 

Landauer's  Spectrum  Analysis.     (Tingle.) 8vo,  3  oo 

Le  Chatelien's  High-temperature  Measurements.  (Boudouard — Burgess.)  12010,  3  oo 

Lob's  Electrolysis  and  Electrosynthesis  of  Organic  Compounds.  (Lorenz.)  i2mo  i  oo 

9 


50 
50 
50 
50 

00 


•••'  Lyons's  Treatise  on  Electromagnetic  Phenomena.   Vols.  I.  and  II.  8vo,  each,  6  oo 

*  Michie's  Elements  of  Wave  Motion  Relating  to  Sound  and  Light 8vo,  4  oo 

Niaudet's  Elementary  Treatise  on  Electric  Batteries.     (Fishback.) lamo,  2  50 

*  Rosenberg's  Electrical  Engineering.     (Haldane  Gee — Kinzbrunner.).  .  .8vo, 

Ryan,  Norris,  and  Hoxie's  Electrical  Machinery.     Vol.  1 8vo, 

Thurston's  Stationary  Steam-engines 8vo, 

*  Tillman's  Elementary  Lessons  in  Heat 8vo, 

Tory  and  Pitcher's  Manual  of  Laboratory  Physics Small  8vo, 

Hike's  Modern  Electrolytic  Copper  Refining 8vo,  3  oo 

LAW. 

*  Davis's  Elements  of  Law 8vo,  2  50 

*  Treatise  on  the  Military  Law  of  United  States 8vo,  7  oo 

Sheep,  7  50 

Manual  for  Courts-martial i6mo,  morocco,  i  50 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture  8vo,  5  oo 

Sheep,  5  50 

Law  of  Contracts 8vo,  3  oo 

Winthrop's  Abridgment  of  Military  Law i2mo,  2  50 

MANUFACTURES. 

Bernadou's  Smokeless  Powder — Nitro-cellulose  and  Theory  of  the  Cellulose 

Molecule .' i2mo,  2  50 

Holland's  Iron  Founder i2mo,  2  50 

".The  Iron  Founder,"  Supplement i2mo,  2  50 

Encyclopedia  of  Founding  and  Dictionary  of  Foundry  Terms  Used  in  the 

Practice  of  Moulding ' i2mo,  3  oo 

Eissler's  Modern  High  Explosives 8vo,  4  oo 

Effront's  Enzymes  and  their  Applications.     (Prescott.) 8vo,  3  oo. 

Fitzgerald's  Boston  Machinist i2mo,  i  oo 

Ford's  Boiler  Making  for  Boiler  Makers i8mo,  i  oo 

Hopkin's  Oil-chemists'  Handbook 8vo,  3  oo 

Keep's  Cast  Iron 8vo,  2  50 

Leach's  The  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control Large  8vo,  7  50 

Matthews's  The  Textile  Fibres 8vo,  3  50 

Metcalf's  Steel.     A  Manual  for  Steel-users i2mo,  2  oo 

Metcalfe's  Cost  of  Manufactures — And  the  Administration  of  Workshops. 8vo,  5  oo 

Meyer's  Modern  Locomotive  Construction 4to,  10  oo 

Morse's  Calculations  used  in  Cane-sugar  Factories i6mo,  morocco,  i  50 

*  Reisig's  Guide  to  Piece-dyeing 8vo,  25  oo 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Smith's  Press-working  of  Metals 8vo,  3  oo 

Spalding's  Hydraulic  Cement i2mo,  2  oo 

Spencer's  Handbook  for  Chemists  of  Beet-sugar  Houses.    ..  .  i6mo,  morocco,  3  o^ 

Handbook  for  Sugar  Manufacturers  and  their  Chemists.  .  i6mo,  morocco,  -j.  oo 

Taylor  and  Thompson's  Treatise  on  Concrete,  Plain  and  Reinforced 8vo,  5  oo 

Thurston's  Manual  of  Steam-boilers,  their  Designs,  Construction  and  Opera- 
tion  8vo,  5  oo 

*  Walke's  Lectures  on  Explosives 8vo,  4  oo 

Ware's  Manufacture  of  Sugar.     (In  press.) 

West's  American  Foundry  Practice i2mo,  2  50 

Moulder's  Text-book i2mo,  2  50 

1  A 


Wolff's  Windmill  as  a  Prime  Mover '. 8vo,    3  oo 

Wood's  Rustless  Coatings:   Corrosion  and  Electrolysis  of  Iron  and  Steel.  .8vo,    4  oo 


MATHEMATICS. 

Baker's  Elliptic  Functions ; 8vo,  i  S® 

*  Bass's  Elements  of  Differential  Calculus i2mo,  4  oo 

Briggs's  Elements  of  Plane  Analytic  Geometry i2mo,  i«oo 


Compton's  Manual  of  Logarithmic  Computations i2mo, 

Davis's  Introduction  to  the  Logic  of  Algebra 8vo, 

*  Dickson's  College  Algebra Large  i2mo, 

*  Introduction  to  the  Theory  of  Algebraic  Equations .  .Large  i2mo, 

Emch's  Introduction  to  Projective  Geometry  and  its  Applications 8vo, 

Halsted's  Elements  of  Geometry 8vo, 

Elementary  Synthetic  Geometry , 8vo, 


Rational  Geometry .  i2mo, 

^.Johnson's  (J.  B.)  Three-place  Logarithmic  Tables:   Vest-pocket  size. paper,  15 

ipo  copies  for  5  oo 

*  Mounted  on  heavy  cardboard,  8X  10  inches,  25 

10  copies  for  2  oo 

Jehnson's  (W.  W.)  Elementary  Treatise  on  Differential  Calculus .  .  Small  8vo,  T;  oo 

Johnson's  (W.  W.)  Elementary  Treatise  on  the  Integral  Calculus. Small  8vo,  i  50 

Johnson's  (W.  W.)  Curve  Tracing  in  Cartesian  Co-ordinates i2mo,  i  oo 

Johnson's  (W.  W.)  Treatise  on  Ordinary  and  Partial  Differential  Equations. 

Small  8vo,  3  50 

Johnson's  (W.  W.)  Theory  of  Errors  and  the  Method  of  Least  Squares.  i2mo,  i  50 

*  Jehnson's  (W.  W.)  Theoretical  Mechanics i2mo,  3  oo 

Laplace's  Philosophical  Essay  on  Probabilities.     (Truscott  and  Emory.) .  i2mo,  2  oo 

*  Ludlow  and  Bass.     Elements  of  Trigonometry  and  Logarithmic  and  Other 

Tables 8vo,  3  oo 

Trigonometry  and  Tables  published  separately Each,  2  oo 

*  Ludlow's  Logarithmic  and  Trigonometric  Tables 8vo,  i  oo 

Maurer's  Technical  Mechanics 8> _ ,  4  oo 

Merriman  and  Woodward's  Higher  Mathematics 8vo,  5  oo 

Merriman's  Method  of  Least  Squares 8vo,  2  oo 

Rice  and  Johnson's  Elementary  Treatise  on  the  Differential  Calculus. .  Sm.  8vo,  3  oo 

Differential  and  Integral  Calculus.     2  vols.  in  one Small  8vo,  2  50 

Wood's  Elements  of  Co-ordinate  Geometry 1 8vo,  2  oo 

Trigonometry:  Analytical,  Plane,  and  Spherical « i2mo,  i  oo 


MECHANICAL  ENGINEERING. 

MATERIALS  OF  ENGINEERING,  STEAM-ENGINES  AND  BOILERS. 

Bacon's  Forge  Practice tamo,  50 

Baldwin's  Steam  Heating  for  Buildings I2mo,  50 

Barr's  Kinematics  of  Machinery 8vo,  50 

*  Bartlett's  Mechanical  Drawing 8vo,  oo 

*  "  "         Abridged  Ed 8vo,         50 

Benjamin's  Wrinkles  and  Recipes i2mo,        oo 

Carpenter's  Experimental  Engineering- 8vo,    6  oo 

Heating  and  Ventilating  Buildings 8vo,    4  oo 

Gary's  Smoke  Suppression  in  Plants  using  Bituminous  Coal.     (In  Prepara- 
tion.) 

Clerk's  Gas  and  Oil  Engine Small  8vo,    4  oo 

Coolidge's  Manual  of  Drawing 8vo,  paper,     i  oo 

Coolidge  and  Freeman's  Elements  of  General  Drafting  for  Mechanical  En- 
gineers.  ,,.... Oblong  4to,    2  50 

11 


Cromwell's  Treatise  on  Toothed  Searing i2mo,  i  50 

Treatise  on  Belts  and  Pulleys i2mo,  i  50 

Durley's  Kinematics  of  Machines.  „ 8vo,  4  oo 

Flather's  Dynamometers  and  the  Measurement  of  Power. i2mo,  3  oo 

"*  Rope  Driving i2mo,  2  oo 

Gill's  Gas  and  Fuel  Analysis  for  Engineers i2mo,  i  25 

Hall's  Car  Lubrication.  . I2mo,  i  oo 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  morocco,  2  50 

Button's  The  Gas  Engine 8vo,  5  oo 

Jamison's  Mechanical  Drawing 8vo,  2  50 

Jones's  Machine  Design: 

Part  I.     Kinematics  of  Machinery 8vo,  i  50 

Part  II.     Form,  Strength,  and  Proportions  of  Parts 8vo,  3  oo 

Kent's  Mechanical  Engineers'  Pocket-book i6nio,  morocco,  5  oo 

Kerr's  Power  and  Power  Transmission 8vo,  2  oo 

Leonard's  Machine  Shop,  Tools,  and  Methods.     (In  press.) 

Lorenz's  Modern  Refrigerating  Machinery.     (Pope,  Haven,  and  Dean.)     (In  press.) 

MacCord's  Kinematics;   or,  Practical  Mechanism 8vo,  5  oo 

Mechanical  Drawing 4to,  4  oo 

Velocity  Diagrams 8vo,  i  50 

Mahan's  Industrial  Drawing.     (Thompson.) 8vo,  3  50 

Poole's  Calorific  Power  of  Fuels 8vo,  3  oo 

Reid's  Course  in  Mechanical  Drawing 8vo,  2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design. 8vo,  3  oo 

Richard's  Compressed  Air I2mo,  i  50 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  oo 

Smith's  Press-working  of  Metals.  . . 8vo,  3  oo 

Thurston's   Treatise   on   Friction  and   Lost  Work   in   Machinery   and   Mill 

Work.. 8vo,  3  oo 

Animal  as  a  Machine  and  Prime  Motor,  and  the  Laws  of  Energetics .  i2mo,  i  oo 

Warren's  Elements  of  Machine  Construction  and  Drawing ,  .  .  .  8vo,  7  50 

Weisbach's    Kinematics    and    the    Power    of    Transmission.     (Herrmann — 

Klein.) 8vo,  5  oo 

Machinery  of  Transmission  and  Governors.     (Herrmann — Klein.).  .8vo,  5  oo 

Wolff' s  Windmill  as  a  Prime  Mover 8vo,  3  oo 

Wood's  Turbines 8vo,  2  50 


MATERIALS   OF   ENGINEERING. 

Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  50 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering.    6th  Edition. 

Reset 8vo,  7  50 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

Johnson's  Materials  of  Construction 8vo,  6  oo 

Keep's  Cast  Iron 8vo,  2  50 

Lanza's  Applied  Mechanics 8vo,  7  50 

Martens's  Handbook  on  Testing  Materials.     (Henning.) 8vo,  7  50 

Merriman's  Text-book  on  the  Mechanics  of  Materials 8vo,  4  oo 

Strength  of  Materials I2mo,  i  oo 

Metcalf's  Steel.     A  manual  for  Steel-users I2mo.  2  oo 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Smith's  Materials  of  Machines I2mo,  i  oo 

tthurston's  Materials  of  Engineering 3  vols.,  8vo,  8  oo 

Part  II.     Iron  and  Steel 8vo,  3  So 

Part  HI.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Text-book  of  the  Materials  of  Construction 8vo,  5  o« 

12 


Wood's  (De  V.)  Treatise  on  the  Resistance  of  Materials  and  an  Appendix  on 

the  Preservation  of  Timber 8vo,    2  oo 

Wood's  (De  V.)  Elements  of  Analytical  Mechanics. 8vo,    3  oo 

food's  (M.  P.)  Rustless  Coatings:    Corrosion  and  Electrolysis  of  Iron  and 

SteeL ' 8vo,    4  oo 


STEAM-ENGINES  AND  BOILERS. 

Berry's  Temperature-entropy  Diagram. I2mo,  i  25 

Carnot's  Reflections  on  the  Motive  Power  of  Heat.     (Thurston.) i2mo,  i  50 

Dawson's  "  Engineering  "  and  Electric  Traction  Pocket-book. . . .  i6mo,  mor.,  5  oo 

Ford's  Boiler  Making  for  Boiler  Makers i8mo,  i  oo 

Goss's  Locomotive  Sparks 8vo,  2  oo 

Hemenway's  Indicator  Practice  and  Steam-engine  Economy i2mo,  2  oo 

Hutton's  Mechanical  Engineering  of  Power  Plants 8vo,  5  oo 

Heat  and  Heat-engines 8vo,  5  oo 

Kent's  Steam  boiler  Economy 8vo,  4  oo 

Kneass's  Practice  and  Theory  of  the  Injector 8vo,  i  50 

MacCord's  Slide-valves 8vo,  2  oo 

Meyer's  Modern  Locomotive  Construction, . ., 4to,  10  oo 

Peabody's  Manual  of  the  Steam-engine  Indicator I2mo.  i  50 

Tables  of  the  Properties  of  Saturated  Steam  and  Other  Vapors 8vo,  i  oo 

Thermodynamics  of  the  Steam-engine  and  Other  Heat-engines 8vo,  5  oo 

Valve-gears  for  Steam-engines 8vo,  2  50 

Peabody  and  Miller's  Steam-boilers.  , 8vo,  4  oo 

Pray's  Twenty  Years  with  the  Indicator Large  8vo,  2  50 

Pupin's  Thermodynamics  of  Reversible  Cycles  in  Gases  and  Saturated  Vapors. 

(Osterberg.) i2mo,  i  25 

Reagan's  Locomotives:  Simple   Compound,  and  Electric i2mo,  2  50 

Rontgen's  Principles  of  Thermodynamics.     (Du  Bois.) 8vo,  5  oo 

Sinclair's  Locomotive  Engine  Running  and  Management i2mo,  2  oo 

Smart's  Handbook  of  Engineering  Laboratory  Practice i2mo,  2  50 

%iow's  Steam-boiler  Practice 8vo,  3  oo 

Spangler's  Valve-gears 8vo,  2  50 

Notes  on  Thermodynamics i2mo,  i  oo 

Spangler,  Greene,  and  Marshall's  Elements  of  Steam-engineering 8vo,  3  oo 

Thurston's  Handy  Tables 8vo,  i  50 

Manual  of  the  Steam-engine 2  vols.,  8vo,  10  oo 

Part  I.     History,  Structure,  and  Theory 8vo,  6  oo 

Part  II.     Design,  Construction,  and  Operation 8vo,  6  oo 

Handbook  of  Engine  and  Boiler  Trials,  and  the  Use  of  the  Indicator  and 

the  Prony  Brake 8vo,  5  oo 

Stationary  Steam-engines 8vo,  2  50 

Steam-boiler  Explosions  in  Theory  and  in  Practice i2mo,  i  50 

Manual  of  Steam-boilers,  their  Designs,  Construction,  and  Operation 8vo,  5  oo 

Weisbach's  Heats  Steam,  and  Steam-engines.     (Du  Bois.) 8vo,  5  oo 

Whitham's  Steam-engine  Design 8vo,  5  oo 

Wilson's  Treatise  on  Steam-boilers.     (Flather.) i6mo,  2  50 

Wood's  Thermodynamics!  Heat  Motors,  and  Refrigerating  Machines. .  .8vo,  4  oo 


MECHANICS  AND  MACHINERY. 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  50 

Chase's  The  Art  of  Pattern-making I2mo,  2  50 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

13 


Church's  Notes  and  Examples  in  Mechanics 8vo,  2  GJ 

Compton's  First  Lessons  in  Metal-working i2n:o..  i  Sc. 

Compton  and  De  Groodt's  The  Speed  Lathe i2mo,  i  50 

Cromwell's  Treatise  on  Toothed  Gearing i2mo,  i  50 

Treatise  on  Belts  and  Pulleys. i2mo,  i  50 

Dana's  Text-book  of  Elementary  Mechanics  for  Colleges  and  Schools.  .  i2mo,  i  50 

Dingey's  Machinery  Pattern  Making i2mo,  2  oo 

Dredge's  Record  of  the  Transportation  Exhibits  Building  of  the   World's 

Columbian  Exposition  of  1893 4to  half  morocco,  5  oo 

Du  Bois's  Elementary  Principles  of  Mechanics : 

Vol.      I.     Kinematics 8vo,  3  50 

Vol.    II.     Statics 8vo,  4  oo 

Vol.  HI.     Kinetics 8vo,  3  50 

Mechanics  of  Engineering.     Vol.    I Small  4to,  7  50 

Vol.  II Small  4to,  10  oo 

Durley's  Kinematics  of  Machines 8vo,  4  oo 

Fitzgerald's  Boston  Machinist i6mo,  i  oo 

Flather's  Dynamometers,  and  the  Measurement  of  Power i2mo,  3  oo 

Rope  Driving i2mo,  2  oo 

Goss's  Locomotive  Sparks 8vo,  2  oo 

Hall's  Car  Lubrication I2mo,  i  oo 

Holly's  Art  of  Saw  Filing i8mo,  75 

James's  Kinematics  of  a  Point  and  the  Rational  Mechanics  of  a  Particle.  Sm.8vo,2  oo 

*  Johnson's  (W.  W.)  Theoretical  Mechanics i2mo,  3  oo 

Johnson's  (L.  J.)  Statics  by  Graphic  and  Algebraic  Methods 8vo,  2  oo 

Jones's  Machine  Design: 

Part   I.     Kinematics  of  Machinery 8vo,  i  50 

Part  II.     Form,  Strength,  and  Proportions  of  Parts 8vo,  3  oo 

Kerr's  Power  and  Power  Transmission 8vo,  2  oo 

Lanza's  Applied  Mechanics. 8vo,  7  50 

Leonard's  Machine  Shop,  Tools,  and  Methods.     (In  press.) 

Lorenz's  Modern  Refrigerating  Machinery.      (Pope,  Haven,  and  Dean.)      (In  press.) 

MacCord's  Kinematics;  or,  Practical  Mechanism 8vo,  5  oo 

Velocity  Diagrams 8vo,  i  50 

Maurer's  Technical  Mechanics 8vo,  4  oo 

Merriman's  Text-book  on  the  Mechanics  of  Materials 8vo,  4  oo 

*  Elements  of  Mechanics i2mo,  i  oo 

*  Michie's  Elements  of  Analytical  Mechanics 8vo,  4  oo 

Reagan's  Locomotives:   Simple,  Compound,  and  Electric i2mot  2  50 

Reid's  Course  in  Mechanical  Drawing 8vo,  2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design. 8vo.  3  oo 

Richards's  Compressed  Air i2mo,  i  50 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Ryan,  Norris,  and  Hoxie's  Electrical  Machinery.     Vol.  1 8vo,  2  50 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  oo 

Sinclair's  Locomotive-engine  Running  and  Management i2mo,  2  oo 

Smith's  (O.)  Press-working  of  Metals- 8vo,  3  oo 

Smith's  (A.  W.)  Materials  of  Machines ,. I2mo,  i  oo 

Spangler,  Greene,  and  Marshall's  Elements  of  Steam-engineering 8vo,  3  oo 

Thurston's  Treatise  on  Friction  and  Lost  Work  in    Machinery  and    Mill 

Work 8vo,  3  oo 

Animal  as  a  Machine  and  Prime  Motor,  and  the  Laws  of  Energetics. 

i2mo,  i  oo 

Warren's  Elements  of  Machine  Construction  and  Drawing 8vo,  7  50 

Weisbach's  Kinematics  and  Power  of  Transmission.   ( Herrmann — Klein. ) .  8vo ,    5  oo 

Machinery  of  Transmission  and  Governors.      (Herrmann — Klein. ).8vo,  5  oo 

Wood's  Elements  of  Analytical  Mechanics 8vo,  3  oo 

Principles  of  Elementary  Mechanics I2mo,  i  25 

Turbines 8vo.  2  50 

The  World's  Columbian  Exposition  of  1893 4to,  i  oo 

14 


METALLURGY. 

Fgleston's  Metallurgy  of  Silver,  Gold,  and  Mercury: 

Vol.    I.     Silver 8vot  7  50 

Vol.  II.     Gold  and  Mercury 8vo,  7  50 

**  Iles's  Lead-smelting.     (Postage  9  cents  additional) i2mo,  2  50 

Keep's  Cast  Iron 8vo,  2  50 

Kunhardt's  Practice  .of  Ore  Dressing  in  Europe 8vo,  i  go 

Le  Chatelier's  High-temperature  Measurements.  (Boudouard — Burgess.  )i2mo,  3  oo 

Metcalf's  Steel.     A  Manual  for  Steel-users-     , i2mo,  2  oo 

Smith's  Materials  of  Machines I2mo,  i  oo 

Thurston's  Materials  of  Engineering.     In  Three  Parts 8vo,  8  oo 

Part    II.     Iron  and  Steel 8vo,  3  50 

Part  III.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Ulke's  Modern  Electrolytic  Copper  Refining 8vo,  3  oo 

MINERALOGY. 

Barringer's  Description  of  Minerals  of  Commercial  Value.    Oblong,  morocco,  2  50 

Boyd's  Resources  of  Southwest  Virginia 8vo,  3  oa 

Map  of  Southwest  Virignia. . .  .'• Pocket-book  form.  2  oo 

Brush's  Manual  of  Determinative  Mineralogy.     (Penfield.) 8vo,  4  oo 

Chester's  Catalogue  of  Minerals 8vo,  paper,  i  oo 

Cloth,  i  25 

Dictionary  of  the  Names  of  Minerals .8vo,  3  50 

Dana's  System  of  Mineralogy Large  8vo,  half  leather,  12  50 

First  Appendix  to  Dana's  New  "  System  of  Mineralogy.'* Large  8vo,  i  oo 

Text-book  of  Mineralogy 8vo,  4  oo 

Minerals  and  How  to  Study  Them I2mo,  i  50 

Catalogue  of  American  Localities  of  Minerals Large  8vo,  i  oo 

Manual  of  Mineralogy  and  Petrography i2mo-  2  oo 

Douglas's  Untechnical  Addresses  on  Technical  Subjects i2mo,  i  oo 

Eakle's  Mineral  Tables 8vo,  i  25 

Egleston's  Catalogue  of  Minerals  and  Synonyms 8vo,  2  50 

Hussak's  The  Determination  of  Rock-forming  Minerals.    (Smith. ).  Small  8vo,  2  oo 

Merrill's  Non-metallic  Minerals:   Their  Occurrence  and  Uses 8vo,  4  oo 

*  Ponfield's  Notes  on  Determinative  Mineralogy  and  Record  of  Mineral  Tests. 

8vo. paper,  o  50 
Roseabusch's   Microscopical   Physiography   of   the   Rock-making  Minerals. 

(Iddings.) 8vo.  5  oo 

*  Tillman's  Text-book  of  Important  Minerals  and  Rocks ,  .8vo.  2  oo 

Williwns's  Manual  of  Lithology 8vo,  3  oo 

MINING. 

fceard'a  Ventilation  of  Mines I2mo.  2  50 

Boyd's  Resources  of  Southwest  Virginia 8vo,  3  oo 

Map  of  Southwest  Virginia Pocket  book  form,  2  oo 

Douglas's  Untechnical  Addresses  on  Technical  Subjects i2mo.  i  oo 

*  Drici;er's  Tunneling,  Explosive  Compounds,  and  Rock  Drills.  .4to,hf.  mor  25  oo 

Eissler's  Modern  High  Explosives 8vo  4  oo 

Fowler's  Sewage  Works  Analyses i2mo  2  oo 

Goodyear's  Coal-mines  of  the  Western  Coast  of  the  United  States i2mo.  2  50 

Ihlseng's  Manual  of  Mining • 8vo,  5  oo 

**  Iles's  Lead-smelting.     (Postage  QC.  additional.) I2mo.  2  50 

Kunhardt's  Practice  of  Ore  Dressing  in  Europe 8vo.  i  50 

O'DriscoU's  Notes  on  the  Treatment  of  Gold  Ores „ 8vo,  2  oo 

*  Walke's  Lectures  on  Explosives 8vo,  4  oo 

Wilson's  Cyanide  Processes I2mo[  i  50 

Chlertnation  Process i  jmo  i  5O 

15 


Wilson's  HydrauLw  and  Placer  Mining i2mo,    2  oo 

Treatise  on  Practical  and  Theoretical  Mine  Ventilation i2mo,    i  as 

SANITARY  SCIENCE. 

Folwell's  Sewerage.     (Designing,  Construction,  and  Maintenance.) 8vo, 

Water-supply  Engineering 8vo, 

Fuertes's  Water  and  Public  Health i2mo, 

Water-filtration  Works iamo, 

Gerhard's  Guide  to  Sanitary  House-inspection i6mo, 

Goodrich's  Economic  Disposal  of  Town's  Refuse Demy  8vo, 

Hazen's  Filtration  of  Public  Water-supplies 8vo, 

Leach's  The  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control 8vo,    7 

Masou's  Water-supply.  (Considered  principally  from  a  Sanitary  Standpoint)  8vo,    4 

Examination  of  Water.     (Chemical  and  Bacteriological.) i2mo,    i 

Merriman's  Elements  of  Sanitary  Engineering 8vo,    2 

Ogden's  Sewer  Design i2mo,    2 

Prescott  and  Winslow's  Elements  of  Water  Bacteriology,  with  Special  Refer- 
ence to  Sanitary  Water  Analysis I2mo,    i 

*  Price's  Handbook  on  Sanitation i2mo,    i 

Richards's  Cost  of  Food.     A  Study  in  Dietaries I2mo,     i 

Cost  of  Living  as  Modified  by  Sanitaiy  Science i2mo,    i 

Richards  and  Woodman's  Air,  Water,  and  Food  from  a  Sanitary  Stand- 
point  8vo, 

*  Richards  and  Williams's  The  Dietary  Computer 8vo, 

Rideal's  Sewage  and  Bacterial  Purification  of  Sewage 8vo, 

Turneaure  and  Russell's  Public  Water-supplies 8vo, 

Von  Behring's  Suppression  of  Tuberculosis.     (Bolduan.) i2mo, 

Whipple's  Microscopy  of  Drinking-water 8vo, 

Woodhull's  Notes  on  Military  Hygiene i6mo, 

MISCELLANEOUS. 

De  Fursac's  Manual  of  Psychiatry.     (Rosanoff  and  Collins.).  . .  .Large  12 mo,    2 
Emmons's  Geological  Guide-book  of  the  Rocky  Mountain  Excursion  of  the 

International  Congress  of  Geologists,  i Large  8vo,     i 

Fen-el's  Popular  Treatise  on  the  Winds 8vo.    4 

Haines's  .American  Railway  Management i2mo,    2 

Mott's  Composition,  Digestibility,  and  Nutritive  Value  of  Food.  Mounted  chart,    i 

Fallacy  of  the  Present  Theory  of  Sound i6mo,    i 

Ricketts's  History  of  Rensselaer  Polytechnic  Institute,  1824-1894.. Small  8vo, 

Rostoski's  Serum  Diagnosis.     (Bolduan.) i2mok 

Rotherham's  Emphasized  New  Testament Large  8vo, 

Steel's  Treatise  on  the  Diseases  of  the  Dog 8vo, 

Totten's  Important  Question  in  Metrology. 8vo, 

The  World's  Columbian  Exposition  of  1893 4*o, 

Von  Behring's  Suppression  of  Tuberculosis.     (Bolduan.) i2mo, 

Winslow's  Elements  of  Applied  Microscopy i2mo, 

Worcester  and  Atkinson.     Small  Hospitals,  Establishment  and  Maintenance; 
Suggestions  for  Hospital  Architecture :  Plans  for  Small  Hospital .  12 mo, 

HEBREW  AND  CHALDEE  TEXT-BOOKS. 

Green's  Elementary  Hebrew  Grammar iamo, 

Hebrew  Chrestomathy 8vo» 

Gesenius's  Hebrew  and  Chaldee  Lexicon  te  the  Old  Testament  Scriptures. 

(Tregelles.) .t*fffz*rz=z=sesa!a..  .Small  4*0,  half  morocco, 

Letter's  Hebrew  Bible ^^^^A^^. 8vo, 


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